Document RJ9d24zk36vj7NQezqejGGBD8
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\
PROPERTIES GRADES SHAPES AND SIZES
Micarta
... time-proved industrial plastic
No materials oifer more limitless possibilities to designer or engineer than plastics, tor plastics have proved in actual service that they provide distinct advantages over materials they have been used to replace. It is not fully recognized, however, that the properties of plastics vary as widely as those of metals. A plastic suitable for a toothbrush handle is by no means suited for use in a tail shaft bearing. Lack of understanding of the properties obtainable in plastics has unfortunately resulted in misapplications. Westinghouse Micarta is distinctly an industrial plastic. While by no means lacking decorative appeal, it has the properties demanded in the severest of industrial service. It is the "steel" of the plastics field. Micarta is the product of 40 years of continuous development and improvement. Micarta has U. S. Army and U. S. Navy acceptance and is unexcelled where strength, lightweight and wearing qualities are essential. This Data Book on Micarta has been designed as a working tool for the designer and user of industrial materials. It presents clearly and completely the technical facts about Micarta--the grades and forms in which it is supplied and the chemical, mechanical and electrical prop erties of each. We believe it will prove a useful guide in the proper selection and application of industrial plastics. However, if you have a special problem involving the used plastics, a Micarta Specialist will gladly help provide the "know-how" to im prove your product design, cut product costs and boost output.
Produced 3/93
Contents
Page How Micarta is Used--and Why......................................................... 4
How Micarta is Made...........................................................................6 Manufacture of Micarta.....................................................................4
Laminated Micarta
Grade Selection Table.................................
10
Standard Shapes and Sizes...........................
11
Mechanical and Electrical Tube Properties ...
Physical Properties--Rods...........................
13
Tolerances--Angles, Channels, Rods, Zees and Plates
Tolerances--Tubing ..............................................
Application of Directional Loads................
16
Physical Properties ....................................................
12
14 15
17
Molded Micarta
Grade Selection Table.............................................. 18 ^,
Properties ................................................................
19
Design Suggestions........................................ ..... .
20
Micarta "444"
Fabricating Micarta "444" ................................... Performance..............................................
20 25
Machining Data
Data
37-42
3
ProdnrArl !VQ3
0700678c
Micaita Serves all Industries
Micarta has proved itself in the "tough jobs" of Industry for more than a third of a century. Some of the most important uses in which its properties have proved superior to other materials cure:
Pulleys, antenna masts, lair-leads,
ammunition chutes, data cases, valve parts, instrument panels, knobs, han dles, landing strut bearings and struc tural angles and channels.
Propeller shaft and rudder stock
bearings, pintle bushings, switchboard
panels, pulleys in mechanical telegraph
systems, gears, pump valves, piston
rings.
.
Switchboard panels, channels, termi nal blocks, armature wedges, terminal strips, bus supports, pull rods, circuit breaker handles, and waterwheel bear ings.
Coil forms, panels, tube sockets, re lay bases, switch spacers, meter and fuse mountings, name plates, supports, terminal boards, switch plates and terminal blocks.
Roll neck bearings, run-out tables, pickle lines, hold-down rolls, up coiler
rolls, punch rolls, carrying rolls and insulators.
Suction box covers, doctor blades,
toe blocks, bearings, shakesprings, table roll covers.
Gears, rayon spin
ning buckets and lin ers, bobbins, bearings, and pulleys.
Plating barrels, valve blocks, tubing, pipe line joint insulation, bubble caps.
MICARTA QUALITIES
SAVES WEIGHT Micarta weighs approxi mately one-half as much as aluminum. Its average density is .05 pounds per cubic inch.
RESISTS COMPRESSION Micarta's great est strength is in compression where pound for pound it exceeds the strength of structural steel. Flexural strength is also extremely high.
RESISTS IMPACT Micarta absorbs impact and will withstand severe shocks in service.
WITHSTANDS VIBRATION The resilience of Micarta enables it to absorb severe vibrations and "cushion" repeated shocks without deteri oration in structure or appearance.
INSULATES LIKE MICA Originally de veloped for electrical use, Micarta is one of the best insulating materials known.
RESISTS CORROSION Micarta is not ma terially affected by acids and alkalis up to 10% concentration. Conditions of continued expo sure to smog, oils, gasoline, or mildly corrosive fumes will not impair its usefulness.
RESISTS COLD AND HEAT Micarta may be applied within a temperature range of minus 80C. (minus 112F.) up to plus 100C. (plus 212F.). Below zero temperatures actually in crease tensile and compressive strengths. High er temperatures increase impact strength con siderably.
RESISTS MOISTURE The moisture resist ance of Micarta is such that the material is not subject to excessive swelling or warping. When used in bearings, its best lubricant is water.
WEARS SLOWLY, EVENLY In many ap plications Micarta wears more slowly than metals. Its uniformity insures smooth, even wear.
REDUCES NOISE Micarta is resilient and dampens vibrations passing through it. When used in mountings, it absorbs vibrations and serves to deaden and reduce noise.
FABRICATES EASILY Micarta may be machined, sawed, drilled, tapped, punched and threaded with ordinary machine tools.
4
Produced 3/Q3
Manufacture of Micarta
In line with the constantly increasing scope oi Micarta applications, Westinghouse facilities for producing Micarta have been expanded by the completion of a new, larger and highly modem plant at Trafford, Pa.
HOW MIC/
Westinghouse Micarta is a heavy-duty, thermo-setting plastic made from fabric or paper impregnated with synthetic resins and compressed under heat into a permanently solid substance with high structural and di electric properties.
Prior to processing, trained technicians check and test all basic raw materials to insure regu larity of performance of the finished Micarta.
The plant is completely staffed for mass production operation. Skilled engineers, de signers and application specialists . . . men qualified to apply Micarta to any production problem are ready to discuss your needs.
A IS MADE
To produce Micarta, paper or fabric is im pregnated with a perfected liquid resin, forced dried and rolled on mandrels or cut into flat sheets. The sheets are then placed between platens of a hydraulic press under high temper ature and pressure. Under these conditions, the final chemical reaction called polymeriza tion occurs, binding the fibrous material into a homogeneous plate of MICARTA.
FORMS OF MICARTA
Micarta may be classified under two general classes by the method of manufacture. The basic materials are common to both classes.
Laminated ... This class includes standard structural shapes: plates, sheets, angles, chan nels, rods, tubes and zees; occasionally in cludes very simple molded shapes. When simple parts can be fabricated by ordinary ma chining operations, or when comparatively small quantities of more complicated shapes are involved, Laminated Micarta is the proper choice. Micarta "444", a form of Laminated
Micarta, will be found discussed at length on pages 29-31.
Molded ... This class includes all miscel laneous molded shapes, formed or molded to shape in molds. For complicated shapes, large production quantities of either simple or com plicated shapes, or for certain properties better obtainable in form molding. Molded Micarta is the choice. It is formed from chopped pieces of impregnated cloth or paper bonded under heat and pressure.
5 07006/9
Produced 3/93
Laminated Micarta
Laminated Micarta is made in a number oi grades for a wide variety of industrial applica tions. Some grades bave characteristics which prescribe their use in mechanical applications. Other grades are especially suited to electrical and chemical uses.
The natural color of Micarta is tan, but some grades are available in black. Grade 213, for example, has a black counterpart. Grade 423 having identical properties.
Laminated Micarta is available in standard sizes of plates, sheets, angles, channels, rods, zees, tubes. Westinghouse has extensive facil
ities for fabricating Micarta to customers speci fications. Westinghouse representatives will be glad to arrange this service. Or, if preferred, Laminated Micarta will be sold in standard shapes for fabrication in customers' plants.
Experience has proved that it is most ex pedient to use Laminated Micarta when a part can be made with simple machining opera tions; or when comparatively small quantities are involved.
The table which follows is intended to aid in making a preliminary selection of the proper Micarta grade for each application.
GRADE SELECTION TABLE
Application Requirements
Micarta
Base NEMA Joint Army-Navy
Grade No. Material Grade
JAN-P-13
Good mechanical strength; electrical characteristics of
secondary importance; dry atmospheres.
213 (tan)
EXAMPLES: Transformer terminal boards; radio parts; 423 (black) tap changer bases; worktable tops; insulating washers.
Kraft paper
X
General electrical properties in both dry and humid atmos pheres--except high voltage or low power factor at high frequency; average mechanical strength.
EXAMPLES: Relay bases; radio parts; switchboard panels.
219 (tan) 429 (black)
Absorbent paper
XX
Electrical applications of primary importance; humid con ditions, power factor up to .035 at frequencies as high as 106 cycles.
EXAMPLES: Communication equipment panels; coil sup ports; radio parts; switchplates, coil forms, terminal boards.
254 (tan) 464 (black)
Absorbent paper
XXX
Intricate punchings; electrical and mechanical properties lower than Grade 219. Moisture resistance and electrical properties intermediate between Grade 213 and 219.
EXAMPLES: Radio tube sockets; terminal strips; insulat ing washers.
222 (tan) 432 (black)
Absorbent paper
P
Mechanical properties of primary importance--especially impact strength.
EXAMPLES: Gears; pinions.
262 (tan)
Coarse weave fabric
C
Mechanical applications requiring impact strength less than Grade 262; low voltage, low frequency electrical performance.
EXAMPLES: Marine switchboard panels; radio parts; small gears and pinions; mounting channels.
286 (tan) 496 (black)
Medium weave fabric
CE
LTS-M-1 LTS-E-2 LTS-E-4 LTS-E-1 LTS-M-4 LTS-EM-1
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Produced 3/93
Laminated Micarta
GRADE SELECTION TABLE (Continued)
Application Requirements
Micarta
Base NEMA Joint Army-Navy
Grade No. Material Grade
JAN-P-13
Primarily mechanical; finished appearance; mechanical strength in
punchings.
238 (tan) Fine weave
EXAMPLES: Fine tooth gears; radio parts; aircraft fairleads.
448 (black) fabric
L
Combination mechanical and electrical applications; toughness; ma chining qualities; appearance; moisture resistance; radio frequency and low power-factor work.
EXAMPLES: Marine relay bases and terminal boards; radio parts.
221A (tan) 431A (black)
Fine weave fabric
LE
Heat resistance (125C); mechanical and electrical strength; fair impact strength.
EXAMPLES: Transformer coil spacers; armature slot wedges; fur naces; rail insulation.
239 (tan)
Asbestos paper
A
Heat resistance (125C) and mechanical strength; best impact strength.
EXAMPLES: Insulation, arc welder handles; armature wedges in railway and mill motors.
200 (tan)
Asbestos fabric
AA
General-purpose, light-duty bearing material; self-lubricating; graphite filled; low coefficient of friction. Not for electrical insulation.
EXAMPLES: Textile mill equipment bearings; piston and packing rings; light-duty thrust washers.
400 (olive green)
Medium weave fabric
Lowest moisture absorption; best dimensional stability; acid and alkali resisting properties; good compressive strength.
EXAMPLES: Pneumatic pistons; wet chlorine gas tubing systems; ball retainers; outdoor fan covering.
273 (tan)
Fine weave fabric
Low moisture absorption and good dimensional stability; resistance to
acids and alkalis.
EXAMPLES: Chemical system valve bodies; plating barrels; suction
box covers.
'
281 (tan)
Medium weave fabric
Low moisture absorption with toughness, fair dimensional stability.
EXAMPLES: Paper mill doctor blades; pump valves; piston and packing rings.
223 (tan)
Coarse weave fabric
Odorless, paper base laminate having good dimensional stability.
EXAMPLES: Refrigerator panels, breaker strips and other applications 263 (tan)
requiring minimum odor and taste.
473 (black)
Kraft Paper
LTS-M-3 LTS-EM-2
LTS-H-1 LTS-MH-1
Fire Resistant Melamine Resin. EXAMPLES: Navy switchboards, panels, mounting channels, angles. 259-2 (gray) Glassweave
Cloth
G5
GMG
7
Produced 3/93
07" 006 /'
Laminated Micarta
STANDARD SHAPES AND SIZES
The following tables give a comprehensive picture of the Tninimnm and maximum dimen sions available in standard structural shapes. The dimensions listed are established by normal manufacturing procedure.
Six types of finish are involved in manufac turing Laminated Micarta. The finishes used on plates, angles, channels and zees are:
Industrial . . . Micarta surface contains small scratches or abrasion marks imparted by mold. No finishing operation is performed.
Satin . . . Micarta surface has a uniform satin appearance.
Glossy . . . Micarta surface has a high lustre.
These finishes are used on rods and tubes: Wax . . . Micarta surface is coated with a wax film, then polished.
Oil . . . Micarta surface is dipped in oil, then rubbed.
Varnish . . . Micarta surface is dipped in varnish producing a gloss. This finish is recommended for outdoor or humid appli cations.
PLATES Length (L) Width (W) Thickness (T)
Mtcsrl*
Grids No.
STANDARD SIZES-Wldth tad Length
I Tan Black 1 48" *95" i 48" x 48"
36" i 72"
36"* 36"
Finish
I1 RaTnhgieekfinnecehses) Mi *4 14. Vi Vs 1 2 '/fa H* VU W V4 1 2 '/fa Vfa
1 2 Vfa Vu vu w Vs
2 s to
T200
22O1iIQy3
4A22O8O38 42y
*
i
mm m
T r221A
222
44aJQJ3*31210RA
IC
"j
M
j j
M
*
M
Bi ITinnnad/Iuuitsestturriiiafalill ItUndUuIUslirlWiil
1
M J M M * _ _ *** __ _
J
or Glossy
j
I^Mi
_
_,,
iIUnUrluUeflirIiQslt Industrial
223 . . . 238 448 239 254 464 O2C5.9O-2 .. . 263 473
m ------
T" M 3
M
Ml mmmm
j MM
Z33J z z3
z z' Zz
5 m
\\ 1 1
Industrial Industrial IiTiInnnntQadiiniuuiUnisesesitixlrrrlitiilaoa*1lil Industrial Glossy
273 ...
281
286 496
4a4a4iNtf
400 ...
Tmi mm m
M I !____
_
si "1
*M*l
M
IM *j
* |
M
l
_ . __
. __ -- --
l
~i i
M M
m *
__
__
,
__
__
__J|---
_
_^
Industrial Industrial IiInn*dduussttrriiaa,lil Glossy
* 288 is not block counterpart of Grad* 200. It it made of an asbestos fabricated, containing woven fine copper wire.
8
Produced 3/93
Laminated Micarta
ANGLES
Length (L) Long Leg (LL)
Short Leg (SL) Thickness (I)
Micarta Grade No.
Tan
Black
L Max.
STANDARD ANGLES
200 239 . . *
213 219
221A 238
423 429
431A 448
48"
262 286 259-2
496
SPECIAL ANGLES
213 221A 238 262
286
423 431A 448
496
120"
liL Max.
9%"
3"
SL Max.
3%"
2"
T
Min.
Max.
Vie"
'/is"
Finish
Industrial Industrial Industrial Industrial , Industrial Industrial Industrial Industrial Industrial
Industrial
Micarta Grade No.
Tan
Black
L Max.
W Min. Max.
D Max.
T
Min.
Max.
STANDARD CHANNELS
200 239
...
213 219
221A 238
423 429
431A 448
48" A"
S%"*
Vie"
A"
262 286 259-2
496
* For shallow channels, these maximum dimensions are reversed.
SPECIAL CHANNELS (NAVY CHANNEL TYPE FBG)
286 12" 2"
259
496
120"
2%" 2%"
4'A"
A" 14"
9
Pmrfi ir-or\ Q lO'i
Finish
Industrial Industrial
Industrial Industrial
Industrial Industrial
Industrial Industrial Industrial
Industrial
006 4
Laminated Micaita
zees
Length
(L)
Inside depth (D)
Leg dimension (W)
Thickness (T)
-i
T
T- .
Micarta Grade Number
Tan
Black
L
D Min. Max.
W Min. Max.
T!
Min. Max.
Finish
200
213 219 221A 238 239 262
286
423 429 431A 448
'' *
496
Industrial
Industrial
Industrial
35'
1%* 9%'
54' 2%' 54'
54'
Industrial
Industrial
Industrial
Industrial
Industrial
Zee ban are available in specific sizes only. Details may be secured from your Westinghpuse representative.
Micarta Grade No.
Tan
219 221A 262 286
259-2 200
Black 429 ) 431A 1 496 j
*** .
DL
Min.
Max.* 54' to 3/ie' D 54' to 1' D 154' to 2' D Standard
Finish Special
3/ie'
54'
12' 36' 2' Grades 219
and 429 only
35'
oa 48'
Wax, Varnish
Sanded oa
Varnish
* Grade 262, only, will be supplied larger than 2' diameter by machining from plate stock.
TUBES
Wall Thickness (T)
Inside Diameter (ID)
Outside Diameter (OD)
Length
(L) '
STANDARD INSIDE DIAMETERS
A " to 3" in steps of ^ inch. 3" to 6" in steps oi inch. 6" to 15" in steps of % inch. 15" to 25" in steps of Vi inch. 25" to 36" in steps of 1 inch. Over 36 inches on request.
--
r O.D.*r
Properties
T
Micarta Similar to
Grade Plate
No. Grade Min. Max.
Numbers
3/is' to /4' ID
L
54' to 3 '*4* ID
54' to 1' ID
Finish
1' ID and Over Standard
Special
52 58* 76 90
97 5A4 94 79
91
93 Black
213 423* 238 219 273 259-2 239 286
200
'4?' 'A?'
V4/ '/is' /is'
'/is' %2*
i/4'l
%' 1' 18'-20' 1'
32"-36"
42'-46" 42'-46'
1'
1' Not Available 32'-36'
32"-36" 32'-36'
1' Not Available Not AvaUable 32"-36' 32'-36'
1' 42"-46' 1' Not Available Not Available Not AvaUable 32'-36"
1' 32 "-36"
oa
Sanded Oil oa
Wax, Varnish
Varnish Varnish Varnish
10
Produced 3/93
Laminated Micarta
`MECHANICAL AND ELECTRICAL PROPERTIES--TUBES
Grade Specific Number Gravity
Ult. Strength
Lba. par Sg. In. Axial Strata
Watar Absorption
Compraasion
Impact % Incraasa Strangth in Watar
(Ft. Lbs.) Altar
T.rala
Diamat-
24 Hours
AxUllr rically
(Lbsj
Dialactric Strength Vfc Wall, Volts par mil
Dry
w.t
Power Factor % at 10* Cycles dry at Agjjrox.
Dielectric Constant 10* Cycles
Surface Resistance (Megohms)
52 1.28 14.000 17,400 70 0.520 3.5
650 350 3.4
58 1.23 14,000 17,400 70 0.520 3.5
450 250 3.4
76 1.30 9,000 20,000 85 0.360 2.8
350 150 3.2
79 1.30 8,000 20,000 80
3.7 85
3.5
90 1.29 11,000 16,500 27 0.206 3.0
450 300 3.7
91" 1.28 6,500 19,000 75
3.1 200 100 3.3
93 1.44 5,000 11)500 65
S.8
94 1.47 6,000 13,500 45 0.163 1.45
25 200
90 7.6
97 1.30 8,500 23,000 85 0.283 1.7
200 150 3.8
5A4 1.67 12,000 13,000 75 3.668
6.5
100
80 0.6
4.5 180,000 4.5 180,000 4.1 150,000 4.2 250,000 4.8 250,000 4.2
lib.ooo
4.3 124,000 4.4 250,000 3.4 120,000
* Testa conducted per ASTM procedure. Values are average and may vary ^20%"
" Special grade ior bearings.
`PHYSICAL PROPERTIES--RODS
w Nema Grade Grade
200
219-429 221A1 431A / 259-2
262
286-496
AA XX LE
...
C CE
Diameter
!4" to 2" Incl. V,e" to 2" Inch 3/,6" to 2" Incl. 3/,6" to 2" IncL 3/6" to 2" IncL 3/,6" to 2" IncL
Specific Gravity
Tensile Strength
PSI
1.93 1.30 1.26 1.97 1.28 1.26
13,500 14,500 13,500 37,000 12,000 15,000
Flexural Strength
PSI
Compressive Strength Axial PSI
Water Absorption After 24 Hours
Immersion 1" Dia.
26,200
20,200
1.61
25,000
25,300
0.93
25,500
29,500
1.22
70,000
68,000
0.60
'
27,500
20,000
1.97
25,000
25,500
0.89
* Tests conducted per ASTM procedure. Values are averages and, may vary_+_2100%%..
LAMINATED MICARTA
Meets the performance Characteristics of A.I.E.E. Standards for Classes A and B Insulating Materials.
11
Prnrii tooH 'VQ'3
?00679
Laminated Micarta
TOLERANCES
In designing any part for Laminated Micarta, designers should take into consideration normal
variations from nominal dimensions. The follow
ing tables give tolerances for standard shapes. Closer tolerances can be obtained by sanding for which there is an increased cost.
RODS
(All grades)
THICKNESS
Nominal Thickness (T)
Paper Base
Fabric Base
. Thickness Tolerance (t)
'/is' 14'
3/l6* '/a'
.015 .016 .020 .024
.015 .020
.024 .030
RIGHT ANGLE (R) Angle Tolerance (r)
May vary from 90 by plus or minus 5 due to distortion.
TWIST AND WARP May be 1% of length.
INSIDE CHANNEL WIDTH (W) " Shrinkage--Approximately .004 per inch of width.
DIAMETER (D) 3/.s* to l'Vie' 2'to 4'
TOLERANCE (d)
.005 .008
LENGTH a)
Tolerance (t) Diameter 0' to 3* 3' to 6' 6' to 12' Over 12
3/.s't0 l'S/,6' .010' .010'
2* to 4*
.010' .015'
WARP
.015' .020'
.030' .030'
Rod Diameter
3/i' to 14' Over !4' to % Over %'
% of Length
PLATE
(by grades)
Nominal Thickness
(T)
(1) 213 254 432
219 263 464 222 423 473 239 429
Vfe' *.0035 '/is' *.005 W *.008
(2) 262 400 444N
*.0065 *.0075 *010
GRADE NUMBERS (Groups 1 and 2)
(2) (1) (1) 223 221A 281 238 273 286 448 431A 496
It It It
Thickness Tolerance (t)
*.0065
*.0075 *.010
*.005 *.006 *.008
W W w %* 1'
l'/a' 1J4' 1%' 2'
214' 3'
*.012 *.021 *.033 *.041 *049
+030
+.048
+.065
+.081
+.097 +.113 +.130
Sanded Both Sides Thickness Inches
Up to .060 incl. Over .060 up to .125 incl. Over .125 up to .250 incl.
Sanded One Side Up to .060 incl. Over .060 up to .125 incl.
Over .125 up to .250 incl.
*015 *024 *033 *.041 *049
+.024 +.042 +.065 +.081 +.097
Tolerances--Inches (Group 1) *.002 *.003 *.005
*.003 *.004 *.007
*012 *021 *033 *041 *049
WARP
Thickness (T)
'/is' to 14' '/a' to 14' Over /2'
Warp and Twist Tolerance (W)
1%) 14% of Length (L) 14%
12
(2) (2) 200 259-2
*013 *014
*019 *024
*.043 *.062 *080
*.010 *.011
*015
*018 *023 *030 *036 *.044 *.049
*055 *.061 *.067 *073
Tolerance--Inches (Group 2) *.003 *.004 .005
*.005 .006 .007
C)
'
Prorlnrod 9/Q.P
Laminated Micarta
TOLERANCES (Continued)
Wall Thickness (T) Less than Hi" Hi" to X" ii" to X" X" to 14" inc.
. Length
0" to 3" 3" to 6" 6" to 12" 12" to 48"
TUBING
Grades 52,58 90,94
.006 .007 .009 .011
WALL THICKNESS
Grades 76.97, SA4
to J*' ID Over 14" ID
=.008 .009
.011 .013
.010 .011 .013
.015
Grade 79
Not made .015 .020 .020
Grades 91,93
Machined to desired tolerance
LENGTH All Grades
Xs" to 2" OD
.010 .010 .015 .030
2" to 4" OD
.010 .015 .020 .030
4" Op and Over
.030 .030 .030 .050
Inside or Outside Diameter
H"to*J6" X" to 1 `Hi" 2" to 4" 4M" to 12H"
DIAMETERS
All Grades EXCEPT 79*. 91. 93. 5A4
ID OD
Inside or Outside Diameter
lili
-H-Hdi-H
.003 .004 .008
.010
**6" to llHi" l'Hi" to3J" 3J^ to 1114"
Grade 93. 5A4
ID
.0035 .005 .008 .010 .015
OD
.008 .010 .015 .025
'Grades No. 79 and 91 should be machined to desired tolerance, and are available at minimum 1*` ID.
WARP
Outside Diameter
X" Over X" to X" Over X"
All Grades
% of Length
2% \% X%
fifra RLdSS
.
APPLICATION OF DIRECTIONAL LOADS
In order to obtain best results from Micarta, consideration should be given to proper direc tion of loading. The examples illustrated on the next page should be used as a guide in apply ing loads. The principles involved in these examples are fundamental and apply to almost all types of loads.
As a key to directional loads, these four def initions should be considered:
Flatwise (F) . . . Load is applied to the flat side of the plate, perpendicular to the laminations.
Edgewise (E) . . . Load is applied to the edge of the plate, parallel to the laminations.
With Grain (W) ... In the direction of the length of the plate, i.e. parallel to cloth warp or lengthwise paper fiber.
Across Grain (C) ... In the direction at right angles to the length of the plate, i.e. parallel to the cloth fill or crosswise paper fiber. As defined above, the term "Grain" is not synonymous with "Laminations".
Minimum bond strength, given on pages 18 and 19, is a relative value through which com parative resistance to splitting between lami nations may be judged. Higher bond strength indicates a greater resistance to splitting.
13 (i *7 --1' --* 7 V
Produced 3/93
Laminated Micaita
WRONG
RIGHT
14
Produced 3/93
07
Laminated Micarta
PROPERTIES
The data in the following tables and curves give a composite picture of the mechanical, electrical, and chemical possibilities and limi tations of Laminated Micarta.
Average values are based on tests made by standard A.S.T.M. methods. All values are for Micarta plate only, and since they are typical averages, variations may be plus or minus 10%.
Other forms (angles, channels, rods, zees, tubes) may show variations depending on the shape involved and direction of pressure in molding. A reasonable precaution would be
to allow for variations 20% below and 10% above the average values for plate.
Space does not permit publishing charac teristic curves for all grades. The following curves indicate the performance of typical grades.
Where heat resistance is a prime factor in design. Grades 200, 239 (asbestos base) and 259-2 (glass base) are used. For continuous operation, the mavinnnn temperature is 125C (257F). Other grades may be operated at this temperature intermittently, but not in excess of 100C (212F) continuously.
-PHYSICAL PROPERTIES OF MICARTA, WOODS AND METALS
Material
Specific Gravity
Tensile Strength Ib**./*sg. in.
Ratio of Modulus of
Ratio of
Compres Elasticity
Tensile Compressive sive in Tension
Strength Strength Strength
CEt)
to Sp. Gr. lbs./sq. in. to 8p. Gr. lbs./eg. in.
Ratio of Et to
Sp. Gr.
Modulus of Elasticity in Compres sion (Ec) lbs./sq. in.
Ratio of Ec to
Sp. Gr.
Micarta 213 Nema Grade X
JAN-P-13 LTS-M-1
1.35
16,000 11,800 38,000 28,100 1.7x106 13x105 0.83xl0 6.2x105
Micarta 219 NemaGradeXX
JAN-P-13 LTS-E-2
1.35
12,000 8,900 31,000 23,000 1.05x106 7.8x105 0.6x106 4.5x105
Micarta 221 A JAN-P-13 LTS-EM-2
1.35
15,000 11,100
35,000 2S,900 1.0x106 7.5 x 10s 0.61 x 106 4.5x105
Micarta 262 Nema Grade C
JAN-P-13 LTS-M-4
1.38
12,000 8,700 35,000 25,400 1.05 xl0 7.6x105 0.56 xl0 4.1x105
Stainless Steel (18-3)
7.85 185,000 23,600 150,000 19,100 30x106 38x105 30x106 38x105
Chrome Molyb denum Steel (Heat-treated)
7.85
180,000 22,900 *150,000 19,100 29 x 106 37x105 29x106 37x105
Aluminum Alloy 2.80 (24-St)
62,000 22,100 40,000 14,300 10.4x106 37x105 10.4x106 37x105
Magnesium Alloy 1.81 (AM-585)
46,000 25,400 35,000 19,300 6.5x106 36x105 6.5x106 36x105
Aircraft Spruce 0.43 (Douglas Fir)
10,000 23,300
5,000 11,600 1.3x106 30x105 1.3x106 30x105
Birch Plywood
0.80
13,100 16,400
5,700 7,100 1.4x106 18x105 1.3x106 16x105
* Yield Foist in Compression. ** Yield Point in Tension. Yield point in compression is substantially equal to yield point in tension in wrought alloys.
D---/.
O/OO
Laminated Micaita
REPRESENTATIVE CURVES
STRESS-STRAIN DIAGRAM (COMPRESSION FLATWISE)
1 ' 139.000
1
34.000 -------j- ccmpkcssio
3N
33.000
4* * 319
363
30.000 x 77X00
<
*
* *
'V
*
* S'
r *
y.
V
*s
.. .'s
'
o 6
y/ / yA
*
>
//
/ *
// /
TJ7Z. u _____ 1_____1_____
A -- 1- -- - - <-0.6 X 10* Mr _1------- 1------- 1-------
--J
A A*-
- tc0J4 X 10* 1 1 {--
- E<-0.61 X IV
0 .01 .03 .03 J04 AS J06 JOT .0% J09 .10 .11 .13 .13
omccnoN m nchcs
STRESS-STRAIN DIAGRAM (TBMSION WITH GRAIN)
STRESS-STRAIN DIAGRAM (COMPRESSION EDGEWISE) STRESS-STRAIN DIAGRAM (TENSION ACROSS GRAIN)
tiNCTHwisc
eatcnOH
11,000 X
I.-1.7 X 10*
\ > 2J3
lt-1. X 10* /
21
s o 10,000 at ^
z 6.000
4,000 z
a 3-
/ 319
\ X Cl as 5 X 10*
V
\ It- 1.0 3 X 10*
" .010 .030 .030 ELONGATION M INCHES Kt INCH
STRESS-STRAIN DIAGRAMS (TORSION)
GKAM MtfCTtOM -
^^J^^^SKCWSiwisi
11.000 X
m *>
z ZVIVI 2.000 ">
/
/tTM ' '
^ 262
SI_
Bt--1.1
j x iq.
tt-i. x i 'v'i,-jjkio
.010 .020 .030 ELONGATION IN INCHES PEft MCH
COLUMN STRENGTH
16
n-~ ->rJ n inn
301
Laminated Micaita
REPRESENTATIVE CURVES (Continued)
oo PHYSICAL PROPERTIES
17
O tOO
0 7 00ti Q 0 2
Laminated Micarta
MECHANICAL AND ELECTRICAL PROPEI
Micarta Grade No.
200 213 219 221A 222 223 423 429 431A 432
JOINT ARMY-NAVY JAN-P-13
LTS-MH-1 LTS-M-1
NEMA GRADE
AA X
SPECmC GRAVITY DENSITY (Pounds per cubic inch)
1.8 .063
1.35 .049
MOISTURE ABSORPTION (% Increase in Weight) 1' * 3' x Thk. as indicated 24 hr.--
25C--A.S.T.M.
Thk.
`/.s' W
1.S 1.0
O.S
6.0 3.2
1.1
LTS-E-2 LTS-EM-2 LTS-E-1
XX LE
P
1.35 .049
1.35 .049
1.38 .050
2.0 1.8 4.0
1.3
1.25
2.0
0.5
0.6S
1.1
1.38 .050
1.8 1.4 0.7
MOISTURE ABSORPTION AT SATURATION (1* x 3' x Vie") (% Increase in Weight)
TENSILE STRENGTH (Pounds per sq. inch)
MODULUS OF ELASTICITY (Tension C--Times 10s)
COMPRESSIVE STRENGTH (Pounds per sq. inch)
MODULUS OF ELASTICITY (Compressive--Times 105)
flexural strength
(Pounds per sq. inch)
4 15 8 5 8 4
W
12000
16000
12000
15000
8000
11500
C
11000
11000
9000
10000
6000
7000
W 1.3 1.7 1
1 .9 1.0
C 1.3 1.1 1 .7 .7
.6
F
49000
38000
31000
38000
22000
37000
E
21000
21000
19000
23000
8000
25000
F 77666 5
E
S
8
6
6
5*
4
FW
25000
27000
16000
21000
13000
19000
FC
24000
20000
13000
18000
11000
17000
EW
24000
27000
16000 21000
13000
18000
EC
24000
20000
13000
18000
11000
15000
SHEAR STRENGTH (Pounds per sq. inch)
FW
FC EW EC
IZOD IMPACT STRENGTH (Foot pounds/inch width)
FW EW
FC EC
BOND STRENGTH (Load in pounds, sample l'xl'x '/') E
HARDNESS (Rockwell "M")
F E
DTFI.TTCTRIC STRENGTH*
F
(Short time method, V./mii. y%* thick) E
DIELECTRIC STRENGTH* (Step by step method, V./mil.
W thick)
F E
DIELECTRIC CONSTANT (At 10* cycles)
DISSIPATION (POWER) FACTOR (At 10* cycles)
12000 12000 12000 12000
7.2 6.2
1100
106 102
100 30
60 20
6.6
0.30
9000 9500 9000 9000
3.0 0.7 2.0 0.6
1000
114 108
500 60
300
45
6.0
0.050
7000 7000 7000 7000
2.0 0.6 1.7 0.5
11000 11000 11000 10000
4.5 1.9 3.4 1.4
950 1800
106 108 103 106
500 360 80 100
360 250 70 80
5.5 5.4
0.040
0.045
6000 7000 7000 8000
6.8
6.7
9500 9000 10500 10000
4.0 1.7 4.0 1.5
1100
104 98
600 80
450 60
5.3
2300
112 109
300 70
200 60
5.7
0.050
0.065
* Property value* of dielectric strength will deviate from specified values by some power of the thickness.
"* Gr
18 07006y03
ProHi irorl 3/Q'}
S --AT ROOM TEMPERATURE --ALL GRADES
Laminated Micarta
238 239 254 262 273 448 464 466
LTS-M-3
LTS-H-1
LTS-E-4 LTS-M-4 TTt
1.35 .049
1.8 .065
1.35 .049
1.38 .050
1.35 .049
1.9 1.5 1.2 2.0 0.9 1.1 1.0 0.8 1.9 0.6
0.8 0.5 0.4 0.9 0.4
281 286 400 259-2 263 444-N 496 473
LTS-EM-1
CE
1.38 .050
1.35 .049
1.38 .050
GMG
G-5
2.0 0.072
1.35 0.049
1.37 0.050
1.2 1.7 4.5 2.4 2.0 Z8 0.9 1.0 2.5 1.6 1.0 ZO
0.6 0.7 1.5 1.0 0.5 1.0
14000 11000
1 .8
40000 21000
21000 19000 21000 18000
11500 11500 12000 11000
5.0 2.3 4.7 1.9
13000 10000
1 .8
41000 10000
25000 18000 23000 17000
7500 6400 9700 7900
2.9 1.7 2.7 1.6
12000 10000
36000 21000
15000 12000 15000 12000
6000 7500 7500 8500
1.4 0.5 1.1 0.4
12000 11000
1 .8
40000 23000
21000 18000 21000 18000
11000 12000 11000 11000
5.4 3.0 5.1 2.8
7000 6000
.8 .8
40000 33000
5 S
17500 9400 15500 9500
11000 10000 13000 10000
1.5 1.0 1.0 0.6
9000 6000
.8 .6
36000 25000
4 5
14000 10000 14000 10000
10000 10000 10000 10000
2.0
'iy
15000 15000
40000 23000
6 6
22000 22000 21000 21000
10000 10000 10000 10000
5.0 2.3 5.0 2.3
11500 7000
1 .6
36000 25000
18S00 10000 17500 10000
7000 7000 7000 7000
44000 25000
2.6 2.1
71000 26000
45000 40000 60000 54000
21000 21000 19000 19000
23.0 12.0 23.0 9.0
18000 14000
1.7 1.1
40000 20000
7 8
28000 23000 29900 23900
9000 9500 9000 9000
3.3
'zo'
13000 11000
0.9 0.9
41000 2S000
26000 23000 26000 23000
10000 10000 10000 10000
5.5 4.6 2.2 1.9
2000
900
950
2200
1600
1500
1800
1200
1800
850
1600
104 110 107 100 115 111 108 106 122 116 114
99 101 10S 97 108 107 104 98
104 104
300 100 700 300 400 350 300 90 30 110 60 60 50 100
500 300 240 60 70
200 60 600 200 250 200 230 65 20 100 50 50 40 80
380 200 130 50 SO
5.8 6.1 4.S 5.8 5.5 5.1 5.4
6.0
0.060
0.20
0.032
0.08
0.055 0.050 0.048
0.015
ilied--no electrical Inaulator.
19
PpoHi
i7/0'3
07006304
Laminated Micarta
CHEMICAL PROPERTIES (Continued)
TBll STRENGTH CHANGE IN 10% ACID SOLUTION GRADE NOS. 200.223. 273. 281
IMPACT STRENGTH CHANGE N 10% AC SOLUTION GRADE NOS. 200, 223, 273. 281
MM o IM IM
caw iMwaaM x lQ5t haSOa soumom *uoc
THICKNESS CHANGE N 10% AOD SOLUTION GRADE NOS. 200, 223, 273. 281
MM
to 120 ISO
______ an kwiwm w log n,Oj townoM at ter c______
WSGHT CHANGE N BOIIJNG AOD SOLUTION GRADE NO. 281
J0
40
*0
>J0
ISO
cays mm w io% hsOa souiuoh at so- c.________
WEIGHT CHANGE IN 10% ALKALI SOLUTION GRADE NOS. 200, 281
10 70 90 40 50 60 TO 00 00 100 110 130 <K| HOOtS 3CAE0 X 10% HI04
WEIGHT CHANGE N S% AUCAU SOLUTION GRADE NOS. 223, 273
10 30 30 AO JO 60 70 M to 100 HO 130 OOj Oats IMMERSED to I0 NeOH SOlimOM AT 70'-30* C
20
70 30 40 JO 60 70 00 90 100 HO 130 130| 0AYS IAOmCCSCO to S% MoON SOlUnOM AT TO*-30* C
n:
Prorli tnori 3/93
Laminated Micarta
CHEMICAL PROPERTIES
BOND STR&JGTH IN 10% ACID SOLUTION GRADE NOS. 200,223, 273, 281
,--------
--
______ m
273
211
223 200 --
lyiiPiSfl
io56 * coats iMMgtsip in
hso,4 soivtion at 50
21
1 r'v/** W O /OO
O/OOkBO
Molded Micaita
Molded Micarta, as contrasted with. Laminated Micarta, is used for complicated shapes, large production quantities of either simple or complicated shapes, or for certain properties obtainable in form molding.
The materials to be placed in the mold may be in one of three forms: (a) impregnated cloth
or paper in laminated form, (b) impregnated cloth or paper chopped into small pieces, or (c) a combination of whole and chopped im pregnated cloth or paper.
The six grades of Molded Micarta listed in preliminary selection chart below have proved highly successful in a variety of applications.
GRADE SELECTION TABLE
Application Requirements
Micarta Grade No.
Base Material
Army
Joint
Air Corps Army-Navy
32212-A JAN-P-14
Type
Type
Fairly low moisture absorption; ordinary electrical char acteristics; good impact strength.
EXAMPLES: Cone rollers, gear webs, terminal blocks.
1321 (tan) Chopped heavy 1345 (black) weave fabric
n
Best resistance to moisture; good compressive strength; best dielectric strength; intricateparts; lowimpactstrength.
EXAMPLES: Rayon spinning bucket liners; pneumatic pistons; fairwater caps.
1360 (tan)
Chopped fine weave fabric
n
Best physical properties; simple designs; good resistance to moisture.
EXAMPLES: Aircraft pulleys; aircraft control quadrants; bell cranks; bomb racks.
1377 (tan) Chopped heavy weave fabric
n
High impact strength; good physical properties. EXAMPLES: Clamps, housings, terminal blocks.
199 (black)
Fabric
n MTS-M-4
Best heat resistance; fair physical properties; low mois ture absorption.
EXAMPLES: Commutators, collector rings; line material couplings; breaker handles.
102 (brown)
Long asbestos
m
MTS-MH-1
General-purpose material; best appearance; fair physical
properties.
107-B (black)
Wood flour
1
MTS-E-1
EXAMPLES: Handles, knobs, cases.
General purpose material; best physical properties; satis factory moisture resistance.
EXAMPLES: Gear webs; castors.
1381 (green)
Chopped heavy weave fabric
22
Produced 3/93
0/00680'.
Molded Micarta
PROPERTIES
Molded Micarta parts of full laminated sheets have properties approaching those of an equivalent grade of Laminated Micarta.
Grades composed of combination sheet and chopped pieces are stronger than those grades containing chopped pieces only. In the latter, the properties generally improve with in creased size of chopped pieces. Intricacy of
design, however, will be sacrificed as piece size increases. Grades composed of short fiber base (e.g. wood flour) are especially adaptable to intricate designs at some reduc tion in strength, particularly impact.
The following test data were obtained by standard A. S. T. M. methods. Compression molded (positive type) samples were used. Values given are typical averages and varia tions may be 20% lower and 10% higher.
CHEMICAL PROPERTIES
23
PrflWi irvaW 0/00
0/00680
Molded Micaita
MECHANICAL AND ELECTRICAL PROPERTIES
134S Micarta Grade Number.......................... 1321
1360
1377
199
102
107B
1381
MAXIMUM OPERATING TEMPERATURE 100C 100C 100C 100C 125C 100C 100C
MOISTURE ABSORPTION (Per cent train in weight; 4' Dia. x J4'-A.S.T.M.-D48-37)............. 2.9 0.8 2.3
1.3 0.2 0.9 3.0
TENSILE STRENGTH (Pounds per sq. inch).............................. 6000
5800
7200
7500
7500
6000
5800
COMPRESSIVE STRENGTH (Pounds per sq. inch).............................. 29000
30000
30000
21000
23000
30000
26000
SHEAR STRENGTH (Pounds per sq. inch).............................. 10000
7500
9700 10000 10000 12000 10000
FLEXURAL STRENGTH (Pounds per sq. inch).............................. 9100
9800 10200 11000 11000 10000 10500
IMPACT STRENGTH (Charpy--ft lbs. per inch--notched)...
3.1
1.2 2.9 3.2
1.2 .55 3.0
DIELECTRIC STRENGTH (Short Time Test--V* thick--volts/mil.) 250 400 250 335 200 350 145
BRINELL HARDNESS (10MM Ball and 5 kg. load)................... 32-40
32-40
32-40
32-40
48
40 34-40
REPRESENTATIVE CURVES--GRADES 1377 AND 1321
PrnHnr'orf 'VQ'5
Molded Micarta
DESIGN SUGGESTIONS
In many cases it maybe possible to substitute Molded Micarta ior some other material without design changes. But in most cases, some re designing will be necessary in order to obtain maximum strength in all proportions.
It is recommended that a Westinghouse
Micarta Specialist be consulted to determine the best material for the application when tho part is redesigned. A Micarta Specialist will suggest economical modifications of design to cut die tools.
Wood or clay models are helpful in deter mining part or mold design, thus saving valu able time and money.
TYPES OF MOLDS
Any one of four commonly used types of molds is employed. Selection depends on the nature of the product--properties re quired, dimensional accuracy, and quantity to be manufactured. In general, the positive
type molded products have higher density and strength properties, although tolerances in the direction of molding pressure cannot be held so tight as with other types of molds. The four most common molds are:
Positive Pressure exerted on whole area of piece. Positive type has no means of expelling excess charge. Semi positive type provided with bleeder openings for overflow of charge.
Filler Plate A modification of flash molds permitting loading or charging without preforming or briquetting. Excess charge expelled or flashed off as in flash molds.
Flash
Excess charge expelled or flashed off through a part ing line or flash between mold members. Normally a preformed or briquetted charge is used in flash type molds.
Transfer
Pressure not exerted on whole area of piece. Instead, charge is forced through small orifice into cavity. This corresponds to the familiar extrusion molding of thermoplastic materials.
25
Produced 3/93
OOo'o
Molded Micaita
DESIGN--CHECK LIST
DIMENSIONS DETERMINED BY FIXED
AND MATED MOLD MEMBERS
Dimensions A and B of the part are fixed by the dimensions of the mold. Dimension C is determined by the relative positions of the mating mold members and depends on the mold stops. Dimension D is the fin variation and is determined by the same factors as dimension C.
Variations from drawing dimensions of molded parts depend upon the following most important factors:
(a) Slight variations in shrinkage of each material due to the difference in molding mixtures from batch to batch. (b) Clearances in mating mold parts and thickness of parting fins. (c) Imperfections, wear, and distortion of -Tnoldg due to the high pressures required far compression molding. (d) Distortions due to stripping molded parts from the mold.
TOLERANCES
In designing products to be made from Molded Micarta, normal commercial tolerances should be given careful attention. Tolerance requirements closer than normal will result in extra mold costs and should be avoided when ever possible.
Tolerances for dimensions like A and B, fixed by the mold, are shown in tolerance curve at the right. These commercial tolerances are recommended and are followed unless closer tolerances are specified on the drawing.
For dimensions like C and D, of sections formed by the relative positions of the mating mold members, with variables resulting from fin variations, tolerances are as follows:
TOLERANCES FOR DIMENSIONS C AND D UNDBl I INCH:
Commercial Close
Readily molded short fiber materials, like wood flour, short asbestos, mica, cotton flock and cellulose.
.008
.005
Longer fiber materials, like fabric, long asbestos, paper pulp and cotton cord.
.015
.008
The tolerances in above table increase in direct pro
portion to the basic dimension when 1 in. and over.
Example: Basic dimension C
in. oi short fibered
materials: The commercial tolerance should be = 2.5 x
.008 = .020 in.
DISTORTION
Molded parts show a slight inherent distor tion due to stripping from the mold or warpage caused by induced internal stresses.
070 26
Prnrll irvsrl fVQ'i
Molded Micarta
SIDEWALL DRAFT
Interior walls, webs, ribs recesses and cavi ties should have a taper of not less than 1. Taper on outside walls is desirable in most designs because it facilitates removal of piece from mold. Production costs increase sharply when taper is not included in outside wall design.
Abrupt changes in wall thickness (A) and undercuts (B) should be avoided.
HOLES AND THREADS
Molded "blind" holes should not have greater length than diameter. Molded "through" holes, if of appreciable length, should be of two diameters; the larger diameter should extend over the greater part of the length.
Fine threads should be avoided because they will be composed chiefly of resins having but little base material for strength.
FILLETS, WEBS AND RIBS
Ample fillets and webs very materially im prove the strength of molded pieces.
LETTERS
All letters or figures should be raised .006 to .009 inch except on parts of high activity warranting hobbed molds. Letters on rounded surfaces should be avoided.
In addition to strengthening the piece, ribs reduce warpage on luge, thin sections.
INSERTS AND ASSEMBLY
Avoid inserts if a satisfactory assembly can be made without them. Assembly costs will be lower if inserts are avoided.
Radii on both sides of the piece should be avoided--better to have radii on one side only.
Straight knurl on inserts prevents insert from turning, but does not prevent insert from pulling out.
0700631 27
Drnrti \r<>r1 O/OO
Molded Micaita
INSERTS AND ASSEMBLY (Continued)
Inserts should not extend close to surface and should be designed to prevent flow of material into threads after molding.
Normally the mold cost for a new design will be absorbed by the customer. Westinghouse, however, will maintain the mold indefinitely.
Threaded inserts extending through or almost through Micarta should be avoided.
Be sure to specify machining of cast inserts at points fitting with mold.
MOLD CAPACITY ,
Provide molds of adequate capacity (number of cavities) to accommodate reasonable in crease in the demand for the product or un usually short delivery schedules. It is desirable that the largest possible volume of production be obtained from each press. In most instances, higher initial investment for molds is justified by lower piece costs.
KNURLS Avoid exterior diamond knurls. Straight
knurls give neater appearance and are less expensive.
PIECE COST
The cost of the molded Micarta product depends upon the following factors listed in order of their importance:
(a) Method of molding: Semiautomatic, hand or benching molding.
(b) Design of parts including inserts, toler ances and finishes.
(c) Tools: Number of cavities.
(d) Materials, both as to prime cost and moldability.
MOLD COST
Molds that can be machined by simple turning, milling and drilling operations will be least expensive. Complicated curves neces sitate making of some molds by hand.
FINISHES Finish A: Very highly polished mirror finish.
Finish B: Smooth surface without tool marks.
Finish C: Smooth surface having some scratches and some tool marks.
0700 28
Micarta "444"
FOR SHAPING PARTS FROM PREMOLDED FLAT SHEETS
Micarta "444'' offers a practical and eco nomical means of obtaining molded forms or shapes with low-cost equipment and dies. Originally developed for the aircraft industry, Micarta "444" has been perfected and ac cepted for use as trim tab fairing, accumulator covers, aviators' chart cases, fuselage tailwheel housings, wing-gun ammunition feeds and ejection chutes.
This form of Micarta, available in tan and
dark green, is a product processed in flat
sheets of various thicknesses from cotton cloth
impregnated with a phenolic resin binder.
"444" fabricates quiddy and easily. To form,
the sheets are subjected to heat and pressure
and formed into various shapes, usually with
inexpensive wooden molds.
.
Designers, engineers and manufacturers will
find Micarta "444" a very practical material
in forming parts where thin metal sheets have
been previously drawn, formed and processed.
FORMING PROCEDURE In order to form Micarta "444", it is neces
sary to heat the sheet stock to within a tem perature range of 250F. to 400F. Parallel hot plates, infrared lamps or ovens, have proved highly satisfactory when heat is uni formly applied to both sides of a "444" sheet, prior to the forming operation. Infrared heat ing has proved to be the best method of pre
heating. When heated to proper forming temper
atures, the sheet is placed in an inexpensive wood mold and is subjected to pressure by screw clamps or by an arbor press at approxi mately 100 pounds per square inch. The Micarta "444" is left to cool in the mold for one or two minutes, depending on the prevail ing conditions and requirements. Pay particu lar note to the extreme angles and curves obtained and illustrated on Page 30.
INTRICATE SHAPES Micarta "444" in tan and green has great
tensile elongation at the forming temperature. They are recommended for forming very deep drawn or highly intricate and complicated shapes having an ultimate elongation of 10% lengthwise, 12% crosswise, and 40% diagon ally. Other properties of "444' are listed in the table on pages 18 and 19.
Bend Radii
Single and compound cuxvatuxes may be formed within these approximate limits
Thick ness
'hr '/is'
'/s'
Minimum Radii
'/.s'
WYt'
29
O/0068
ProHnrvart 9/99
, Micarta "444"
30
D---i. , --i o /no
w Micarta "444"
31
PrriHnrvsH fVQ'?
0700681h
Machining Data
The following machining suggestions are applicable to both Laminated and Molded Micarta.
As a rule, Micarta is machined more readily than metals. Machine Tool operators should be careful to keep the temperature of the workbelow 150C; temperatures above 150C may damage Micarta.
Micarta is machined dry--cutting com pounds and lubricants are unnecessary. Cut tings should be removed by suction.
However, we are hilly equipped to do all types of machining in our fabricating plants, possibly at a much lower cost. We have the proper tools and precision machinery, plus experienced technicians, capable of per forming every machining operation with the minimum waste and spoilage of the Micarta stock.
PUNCHING
All Micarta grades are suitable for either hot or cold punching. Dies must be kept sharp to obtain best results.
Clearance
The minimum clearance between individual
punchings and between punchings and the
edge of the Micarta plate should be three times
the thickness of the plate (D=3T).
'
Die and Punch Design
Dies for punching Micarta are designed as for punching metal, except that smaller clear ances are allowed between punch and die. Strippers are close fitting and backed by strong springs.
Grade No.
200 213 219 221A 222 223 238 239 254
259-2 262 263 273 281 286 400 473
PUNCHING TABLE
Recommended Maximum Thickness
Cold
A* A*
X"
Yb' Ye' Ye'
A'
X'
X'
A*
Ye' *6*
X"
X"
w
Vb"
X'
Hot
Xr w
Ye'
'4* '/4* '/4* '/4*
Yb' Yb'
A* '/4*
X' Ye' Ye'
'/4* 14"
Yb'
Results
Poor Fair Good Good Good Good Good Fair Fair
Fair Good Fair Poor Fair Good Good Fair
Best results are obtainable in hot punching.
32
Since the diameter of punched holes in Micarta shrinks when the punch is removed, the size of the punch should be .001* larger them the desired diameter of the hole for every .020* thickness of material, punched cold, and .001* larger for every .015* thick ness, punched hot
IF............................ T =Thickness of Micarta A =1/40 T (cold) or 1/60 T (hot hd =Hole diameter D = Diameter of punch H = Diameter of die
THEN... Diameter of = hd + (-^q x .001) cold, or punch. (D)
hd + (-^jg a .001) hot
jL/i&meter ox cue \n)
Diameter of _ n / T AAn hole (hd) - D -- (.020 1 -001) cold- or
D -- (-Qjjj x .001) hot
Example:
To obtain a 1.000* diameter hole in A* (.094*) thick
grade 213 by hot punching, use a punch diameter (D)
equal
to hole diameter
(1.000*)
+
(.094 (.015 x
.001)
or 1.006*
and a die diameter (H) equal to punch diameter (D) 4-
2A or 1.006 + (2 x 1/60 x .094) or 1.009*. If the piece
is punched cold, the punch diameter (D) should be
1.005* and the die diameter (H) 1.009*.
0700601
- Heating
Micaita to be hot punched is preheated in a steam or electric oven designed to give uni form heat throughout the heating chamber. Pieces should be well separated. The material should be left in the oven only long enough to become uniformly heated to oven temperature. Further heating will cause brittleness. Tempera tures of 100C to 120C are recommended. Time: S minutes for i/i6* thickness to 30 minutes for !4" thickness.
SHEARING Shears suitable for thin sheet metal are used
for Micarta. The knife blade should be kept sharp.
Machining Data
SHEARING TABLE
Grad* No.
213 219 200
221A 222 223
238 239 254
259-2 262 263
273 281 286
400 473
Maximum Recommended Thickness
Cold 16' Mi' w W*' Mi' 16' 16' 16' 16' 16' Mi' 16' 16' 16' 16' Mi' 16'
Hot
W 'A' '/s'
/s' W W
'/s' /s' W
Mi' 'A'
/s'
Mi' 16'
Hj'
'/s' /s'
Circular Saw Design
SAWING
Band Saws The usual band saw should be used for saw ing blanks from plate stock. Saw blades should have between 4 and 7 teeth per inch, some set. The number of teeth will depend on the width of the saw. Operating speed should be approxi mately 3000 feet per minute. For circular cuts the width of the saw should be small, but for straight cuts the saw blade may be up to 1 inch wide.
33
PrnHnr'oH 'i/O'i
n7006'o J
. Machining Data
Circular Saws
Best results are obtained when the saw Made projects a minimum distance above the sawing table. When extreme smoothness oi cut is desired, place a thin sheet of scrap material under the Micarta.
The Westinghouse design for Micarta circu lar saws is shown on page 33. For thickness up to ^YT use 16" saws; for thickness up to 1", use 12" saws.
Drills should be lifted from the work fre quently to prevent dulling caused by excessive heating. The speed of the drill is considerably in excess of that used for soft steel. With tungs ten-carbide tips, speeds may be as high as 16,000 rpm.
TURNING
Ordinary high-speed tool steel is used in finishing operations for all Micarta grades.
High-speed tool steel is not essential for roughing. About .010" stock, however, should be left for finishing.
In drilling Micarta parallel to laminations (use fabric-base grades only), care must be taken to prevent splitting. The Micarta should
DRILLING AND TAPPING
For all Micarta grades use a standard drill with lips backed off to provide plenty of clearance.
be clamped in a vise or between plates. A "flat" or "bottom" drill is used at about the same speed but with slower feed.
Holes % inch and over may be chucked in a lathe and bored.
These recommendations for drilling also ap ply to tapping.
Drill Size--Because of the nature of plastic material, the diameter of drill selected should
34 0700,681
Machining Data
be about .CC2" larger than the specified diam eter of the hole. The drill should be run at high speed and lifted frequently to remove the chips so as to prevent heating and rapid dulling- In addition to .002" decrease in hole size for a sharp drill, this may decrease as much as .002" more for a dull drill or a total of .004" less than diameter of drill.
MILLING
Standard tools are used at speeds and feeds similar to those for bronze and soft steel.
The cutting angle of the mill will give better results if ground with a slight rake.
Tap Size--If a tight fit is desired for a standard screw, a standard tap as for metal is satisfactory. However, if a loose fit is re quired an oversize tap of about .002" should be used. If the thread is to be used frequently, metal inserts should be used. For tapped holes over Vz" in diameter, it is more desirable to use metal inserts or molded threads.
THREADING
.
When cutting a 60 thread, it is always advisable to swing the compound rest on the lathe to a 30 angle. The tool is ground to cut on one side only.
BUFFING
Standard polishing rouge on a rag wheel gives satisfactory results for Micarta requiring,, a polished surface.
Grinding and sanding may be done by belt, disc, or centerless methods. No lubrication is necessary.
STAMPING AND ENGRAVING
For all other threads, standard methods are used with satisfactory results; the speeds and feeds are similar to those used in threading soft steel.
Micarta surface to be stamped should be
smooth. Sanding may be necessary, in some
cases, to obtain satisfactory results. Compres
sion presses employing heated dies give best
results.
.
Engraving can be done with any standard engraving machine. Tools should be sharp to produce clean-cut edges.
35 07006820
P5 -J-/->
-1 r-tr^r.
Produced 3/93
