Document Yrpq998BaJKVvjdrgRQR019x8

on * turrct Utfc*irfibb pttimbdn*ctf.fro fotttocfc wtths.Jljiifw. (Phoi a>rtiy Ciulh*) FABRICATING CAST PHENOLICS by S. M. COAN ^ gym ALTHOUGH COMPRESSION MOLpWG IN SOME form is almost as old as civilizariBtlTthc fabrication of . cast Rsiiu is a comparatively new industry, and quantity pradofdoo hat bera developed dttriog the pair t<m yean. . The1 advantages of cast tains ate numerous. Almost every imaginable color can be'obtained, and the color and mottle exist throughout. the material. Plain, mottled, opaque, translucent and transparent materials ate available. Arbors, being simple, can be constructed within a very short time, and material requires but from four to twelve days for. curing, depending on color and base. Deliveries of finished parts, can therefore, be made within less, time than .usually required for the pro duction of molds used for other plastics.. A well equipped fabricating plant has departments de voted to all of the various operations, mid is so laid out . that articles going through production travel from ma- chines used on initial opiriatiqns to final polishing, in: speccion and'shipment' withoutunnecessary handling. If the parts are to be turned from sblid rods, the ihaxi' mum number of pieces which can be produced from an individual rod must be calculated with allowance for cutting off, flash and end of rod that is to. be held in the collet when, final .piece. is being turned. An order it placed with the raw material suppliers for the correct . number Of rods, in color and size required, and when these rods are received and checked, it Is fine accessary ' to remove, by a fast grinding operation,' any rough flash that, may extend beyond the greatest diameter at mid of "rod.so that difficulty.will not beencotmtiered wheri feeding through the screw machine. Automatic screw ma, chines are sometimes used, aiid have the idvantage oi speed and low fobpr.cost if volume is large. Tbcirdis: advantage lies in the fact that cast rods average 10 in. in length .and are tapered.slightly.; Unless^rodrrsit '1 centerless ground to remove ihit.taper; tri^k-isSspWr ^ times encountered ;with ' the: longer piece of material must be allowed for^ last jtt :; ; to be turned. As most runs are not over several thousand;' pieces of a design,' hand- screw ^machines';prove^um-'';^ factory^ They can be set up quickly and cxpeniivc-iofm.-: ing tools are not required. - Ball bearing centenandaut- \ mafic die heads for threaded parts are almost a necessity. All forming operations, usually done on brassorother ; metals, can be accomplished if machines are oposted ar correct speed andtools are properly designed:'-' Forming. tools, made of brass and .of steels, of .various hairinesses,. give good results. " - , -- -v.-.' J;- Samples and; small lots can be most,: ecooomicslly , turned on a' hahd;lathe,with hand.'tboli'. ' Hindiiathe; ' operators are usually, skilled men.with qutrc.cftimmatty3'- years' experience turning similar partafrombldefplastjcr. v; They make theirown chucks of brcKue. alumiflutn or', wood, and can chuck and ct-'tKe parc to be twnedin-; a fraction of the time required by ari unsldlll^ bldafor' ' -Si with con ventiorialtools andequiptnent.^ln tbeproduction of bracelets, for example, ic.has.bcefr found, advah-..;. tageous to heat the cylinders for a short'timc.by unmet-. ' lion in hoc water. ^ The. entire cylinder, is placrii on a mandrel and the maxirpum number' of bracelets tbat'ean' be obtained from a cylinder can be turned' before the ' materia) cools. e'.-wa A combination'of line.shafting and unit drive*;.is probably, molt ecotwmical.Some.iperialmachifte* most have their own motors in order fo.ifliurc.consunt.high' speed and belt tension. The plant should k so.arranged ' -'that failure of anyone motor wiil not'delay production' .; more than'a few minutes. : Ball ''M 'if ' `A H-%*?,*' Uqy^ reilftofd: bcln^ouri^lntt>'(cS mcldi which give It the 4ipproxfate jfiipc of ib finuhed. form -... Thcje4re.;plpc.stem-b<ms removed from the'lead molds :>aftcr >days-.of` hardening . at controlled temperature FABRICATING CAST PHENOLICS (Continual from page' iff bearing bangers and short constant tension drives give excellent results. A blower system is essential and usually every machine is equipped with an adjustable connection that will facilitate re moval of dust, fumes and shavings. Castings in special shapes that arc not to be turned are cut into blanks of correct thickness by means of cut-off machines having thin abrasive wheels which rravel at high speed. Each machine must be equipped with a fresh water connection, as a constant flow of clean water is absolutely necessary. A heating unit on the water feed line raises the temperature of the water during the winter months, and prevents the operators' hands from becoming cramped. Each machine must also be piped to remove the water, which is never used over again, and blower connections ate also installed to eliminate fumes. Wheels are relatively inexpensive, and. with proper care requite infrequent changing. They are sharpened by cutting brass pipe or copper tubing with the water supply shut off. The button industry particularly, uses slicing machines that cut button blanks from rods or buckle castings with no waste. Rods are heated by immersion, and the op eration is almost entirely automatic. If, however, close tolerances are required, better results can be obtained by means of abrasive wheels. Very large parts and samples can be readily cue on a band saw. Saws should be of the metal cutting hard edge type, and number of teeth per inch and sec deter mine smoothness of cut.'. Automatic saw sharpening equipment has proved its worth, as saws that have been resharpened give better results than when new, and saw cost is reduced as much as 90 petccnc. If parts are sawed, they musr be surfaced oh a belt or disc sanding machine before bcing'iinishcd. Sanding belts, traveling at fairly high speed, give vety good results. If finished surface is to be fiat, conventional type of machines are used, but belts traveling over cwo pulleys and unsupported in the center are found of great advantage when removing small projections on rounded surfaces or performing othcroperations when a fiat surface is not desired. Pen bases and similar articles are beveled on beveling machines or shapers, having ball bearing spindles. Bronze alloy, brass and steel cutters are used. Cutters should be sharpened only by one skilled in this type of work, and abseiice of. vibration is also important. If tools are improperly sharpenrd or spindle is not true, the work may chip. Irregular shapes, samples and small quantities of pro duction pa.-ts can be easilyjig-sawed. Saws are usually made by the jig-saw operator, as he is thus able to select the number of teeth and set required for a smooth surface. Outline of parts to be sawed may be scratched on the surface of the sheet or a printed pattern pasted to the surface with witcr soluble glue'. If a number of parts are to be cut, several sheets are pinned together. Oiled paper inserted between the sheets lubricates the saw and helps' ro ohtain a smoother surface. Many letters and r^ TP %v Olllrijs of (hit sort .ire , tccomplhhed with phen olic, retini, either'in feed . or robber /nofcb. ' Redio cabinets, end other snail cast . housinas. ire increasirh's in popularity because of the transpar ency cast resins afford. This statuette of Venus -was cast of Cryslle In '"rubber mold by The hrtatblelle . Corporation signs are made in this manner, arid all that is necessary it an inexpensive paper pattern. Very good results arc obtained by using'"cast-in-glass sheets, which have a glass" smooth, surface, and the letters thus require no polishing after they are sawed.. >'!. Small parts may also be blanked from sheets, and this method is often employed by the jewelry'trade, as a supply of sheets in various'colors and thicknesses may be kept on hand and immediate delivery made to the customer, regardless of style changes. ' However, it is much.raorc economical to fabricate parts of this type from"castings, having'outline shape of finished article, as there is a minimum amount of waste. .Jewelry' parts and similar articles can be readily carved. A ball bearing spindle is generally used with either small steel, bronze or brass cutters or shaped abrasive wheels'. Skillful operators can carve hundreds of "pieces with almost no variation in design. Each machine is equipped with a number ofshaped wheels, and wheels may be quickly and easily changed. Original designs arequice often worked out by the operator as ex pensive tools, dies or patterns are not necessary. -Turned parts, having center holes;'are dcilled while being turned, while castings'and odd shaped parts are easily drilled with the usual type of.high speed vertical drill, having its own motor or driven from a,line shaft. Cut resins can be easily tapped bn vertical or horiiqritai tapping machines. Standard taps are used, and greater strength' is obtainedibyiising' fairly''coarse threads. ' Tapped, holes .should.^ ;cht(S'?vyfth plug ggd, a* the abrasive action of the material causes'wear. iSive; screws' .arfdjself-uppingscrcws eliminate the oecettity of pl>p. and are extensively used for at taching jewelry findings and other small metal parts. MODERN PLASTICS Although milling cutters can be used when slotted sectionsare necessary, better results are obtained with' special machines equipped with grinding wheels of cor rect grit and hardness. A constant flow of fresh water on the wheel and the work eliminates "burning" and dust, and helps to provide a smooth surface.1' Wheels have a much longer life if sufficient water is used. If parts, must be formed, electric.steam tables slightly soften the material so that it may be bent to. correct H sHape. Parts may also be'softened by immersion in hot water or by dry heat. . When all machining operations have been completed, articles are ready for finishing. Small parts and those . not requiring a high luster can be tumbled in wood,or ; - wood and steel barrels. There are several concerns that . - manufacture these barrels and supply formulas for finish ing cast resins. .. Larger parts and those on which sharp comers'arid ' edges must be retained should be hand finished through out. There ate several methods, one of the most com- ' raon being an ashing process, followed by finishing on a cotton buff. A thick mixture of fine pumice arid water is applied to the wheel with a wooden paddle, arid when the work is held against the wheel, all topi marks and ; . sand marks are removed.. Another method, used jSriri- - cipaily in the pyroxylin fabricating sections of the couri- .. try, consists of a wheel composed of carpet disks travel ing in a solution of water and sifted anthracite, ashes. The final finish and high gloss that brings out the beauty of the material is secured by polishing on a cotton buff.. One seccibn/of the wheel's face is not coated with.... polishing compound, and when parts have been buffed, ' they are wiped on this dry section. ; Air cooled wheels have been developed that enable the operator to highly , finish the article without danger of friction "burning." ;. V'. After parts are' polished, they are placed in racks or - boxes and carefully handled to avoid scratching. They . - arc now ready to be inspected, counted and snipped. Cast resins have entered the radio field and manu facturers of radios claim improved tone, increased sales . appeal and greater strength. Designs may be simple, as the bcaury of the material alone commands insranr at- ' ` tenrion. Transparent and opaque bowling balls are , rapidly winning favor with expert howlers. In addition to their beauty, it is said that the greater "liveliness" of the material enables the bowler to obtain higher scores. Bowling balls arc cast in glass molds/'The glass is de stroyed v.icn the ball has been cured, and the fabricator removes the neck, turns them to accurate dimensions and finishes them by hand. They are sold ac.^; price thac compares favorably with competitive materials,,''" Streamlined housings have been made for office appli ances and similar articles'. They lend a new touch of beauty and design to otherwise drab equiprrieric. Parts arc made for huge trucks and toy electric' trains,.chro mium arid copper gift articles, lamps and .modern fur- ' ,1 niturc. " Producers of .raw'material, manufacturers and fabricators look forward with optimisrii to a period of development that will far exceed that which has oc curred during the past decade. V- ... . ritish Chemical Supplies, Inc yanamid A Chemical Corp. upany "I Co. S Nemours A Co., Inc., E. I. vneinicai Corp. t; Co., Tar & Chemical I)iv. krodt Chemical Works & Co.. Inc. ato Chemical Co.. ar APCLhAemSiTcaICl CIZoErpR. S fan-British Chemical Supplies. Inc. Cyanamid A Chemical Corp. e & Carbon Chemicals Corp. id Corp. ;"; /r;:'-\rV ' rdal Solvents Corp. BhemicalCo. pt de Nemours A Co., Inc., E. X. Products Co., Inc. fax Corp. es Powder Co- . ries Chemicals, Inc. Chemical Corp. knto Chemical Co. pal Aniline & Chemical Co., Inc. I^OUProducts Co. IflpChemicals, Inc. Ks Products A Chemical Co. (Industrial ChemicalCb., Inc. Its 299-302, this section Bakelite Corp. -General Electric Co., Plastics Dept. Glyco Products Co., Inc. Makalot Corp. Roichhold Chemicals, Inc. Resinous Products A Chemical Co. RESINS, OIL SOLUBLE Bakelite Corp. Beetle .Products Div., American Cyanamid .Co... Durite Plastics, Inc. General Plastics, Inc. Makalot Corp. Reichhold Chemicals, Inc. Resinox Corp. RESINS, PHENOL American Cyanamid A Chemical Corp. Bakelite Corp. Catalin Corp. Durite Plastics, Inc. General Plastics, Inc. Makslot Corp. Marblette Corp. Monsanto Chenu Co., Plastics Div. Reichhoid Chemicals, Inc. Reilly Tar * Chemical Corp. Resinous Products A Chemical Co. Resinox Corp. Rohm A Haas Co. OCTOBER 1938 ^ 287 ik'&k fWocU~v ^ fW `;, -1 < 1' -, l " ,. .'f v -7` . ,; ^ ^', v'>- w \ v>,. _ \-(i .v ^ - - : "> ' , V -y?-;; ::>.'vv>. '>'f\V. :v?'V,iA':> -' y&?yjs.-. ;>>7> , - . - 7 ^v-'.-r. -. 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