stamping manual

8/6/2019 Stamping Manual

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HOW TO DESIGN STAMPINGS By COOPER MANUFACTURING COMPANY- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -In any part designed as a stamping, only the designer knows which dimensions are

critical. If all are critical, this should be clearly indicated; if only certaindimensions are- vital to the functioning of the part, requiring close tolerances onother parts results in needless expense. The producer of stampings frequently wondersin examining the drawings whether the radii must be as sharp as shown, and whetherall holes and slots actually require the same close tolerances. The designer should besure that he needs everything he specifies, because each unnecessary requirementresults in a needless increase in cost of the part. Consultation with a stampingproducer will often lead to economies in production. Since stampings vary so widelyin size, some producers specialize in small parts, others in large, and some cover awide range of sizes.

All metal stamping operations can be classed as either cutting or forming.Cutting operations are those in which' the metal is completely sheared by stressingbeyond the ultimate strength; forming operations are those in which the metal isstressed beyond the yield point and permanently deformed.C UT TIN G O PE P.A TIO NS

Cutting operations are designed to change the outline of the edges of a part orto cut holes in the interior. They include blanking, punching, extruding hbles,piercing and lancing. The requirements of cutting operations are varied and some ofthe most important to be considered for effective design are discussed below.

Blanking -- Blanking is the cutting of shapes out of sheet stock either to producefinished parts or as the first stage in a forming operation. The die is made to siZe,if size is important, and clearance is taken on the punch. If the blank is very large

in relation to the metal thickness, curvature of the sheet may cause measurableinaccuracy in the blank even though the tools are accurate. Since the blank followsthe shape of the punch, it is possible to form shallow shapes simultaneously withblanking; if the face of the punch has a convex contour, the metal is stretched tothat shape before shearihg occurs.

1 n blanking,the pressure required depends on the strength of the stock, and thedepth of penetration before shearing occurs is inversely proportional to the hardness.


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Page 2Depth of penetration appears to be a measure of ductility and it has been suggested,but not definitely proved, that the percentage reduction in thickness in shearing isrelated to the reduction of area in the tensile test.

Since the contour and intricacy of the blank determine the cost of dies, simple

blank contours should be used if possible. It may be less expensive to build up acomponent from several simple parts than to make it as an intricate single part.Straight-sided blanks with corner radii are less expensive than blanks with squarecorners. Sharp pointed corners are even worse than square corners in reducing toollife. Narrow slots also reduce tool life and increase the cost of blanking.

Some of the factors that should be considered in designing for blanking areillustrated in Fig. 1 through 4. These show a few possibilities in blank arrangementto save stock and facilitate production.

Shearing, Parting and Notching -.- These operations differ from blanking becausethe section being cut is unbalanced. Shearing is cutting along a Single, usuallystraight, line and generally generates no additional scrap. Parting produces scrapsince is involves cutting along two parallel lines. Parting has the advantage that itpermits somewhat closer dimensional control than shearing.

Notching is unbalanced blanking with cutting occurring only on three sides of thepunch. Because of the unbalanced forces, the part being cut tends to move away fromthe punch making it difficult to control dimensions as accurately as can be done withblanking. Notches are potential starting points for failures and should not bespecified with a sharp vertex in parts subjected to severe stress conditions. Suggestiofor notching are given in Fig. 5.

Lancing and Slitting -- Lancing is a combined cutting and forming operation oflimited application. It is used to form a louver or similar shape. The cut is usuallya straight line, and bending is restricted to a displacement not more than the thicknessof the stock. Louvers can be lanced and formed in one operationo Design suggestionsare given in Fig. 6.

Slitting is a somewhat similar operation but instead of cutting the stock along astraight line, it often is cut around a portion of the periphery. The tab thus formedis bent in a subsequent operation.


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Page 3.Holes in Stampings -- In blanking and the related operations just described, the

shape cut from the stock was the desired part. In the group of cutting operationsdiscussed here, the shape cut from the blank is scrap material. If holes are requiredin stamped parts, they are formed by punching, extruding or piercing, the distinctionbeing shown graphically in Fig. 7.

In designing for punched holes, it is frequently forgotten that only part of thestock thickness is sheared cleanly, the blance being torn out by the pressure exerted.The hole produced by punching has a taper, not parallel sides. A rule of thumb is thatnot more than one-half the stock is sheared and, as shown in Fig. 8, the hole diameterbelow the sheared areas is significantly larger than that produced by the punch. Thispoint is particularly important if the hole sides are required to act as bearingsurfaces; a subsequent reaming operation may be required to obtain parallel walls.

Round holes are the cheapest an& easiest shape to machine on dies and the easiestto hold within tolerance limits. Hole sizes should be standardized to reduce costs, andpreferably a minimum number of sizes should be used on a single blank. If slots arerequired, round ends can be made cheaper and easier than square ends.

There is a lower limit to hole size below which it is not economical to punchholes because of excessive punch breakage. For mild steel this limit is roughly thestock thickness; generally, it is preferable to drill holes of smaller diameter. Howevesome producers say that punching fine holes is not impractical, but depends on the metalStrasser suggests that the following formula can be used:

Min hole diameter (in.) = 4 s t P0.67 c

where s = shear strength of stock,psi

t = stock thickness, in.p = p un ch p en et ra ti on , %c = compressive strength of

punch, psiIn this formula, the penetration of the punch before the slug is torn out must be

determined for each material and stock thickness. For mild steel some values are:S to ck T hi ck ne ss ,

in. Penetration, 1 01/32 871/8 62114 _ __ _ __ __ ')0


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Page 4.Holes should be located with the distance between the outside edge of the sheet

or the distance between two holes not less than twice the sheet thickness for stock0.06 in. thick or heavier. Metal below this thickness requires a distance not lessthan 1/8 in. Effects of hole location are indicated in Fig. 9.

Hole clearances are determined by service requirements. For a cold rivet, the holshould be 1/64 in. over the nominal rivet size. Bolt clearances are usually 1/64 to1/32 in. for general service requirements, but smaller for aircraft service.

Threaded Holes -- If holes are to be threaded, stock thickness must be no less thaone-half the thread diameter for steel or brass, and at least two-thirds the threaddiameter for softer metals such as aluminum. However, it is not always necessary toincrease the stock thickness to achieve this objective. Extrusion of the stock (seeFig. 7) often increases thickness at the hole to the required value.

If two stampings are to be fastened together, it is desirable to compensate forinaccuracies during manufacture by employing a round hole in one part and a slot in theother. Slots are also used to provide for adjustment in overall length and widthdimensions. Depending on their function, slots mayor may not require gage inspection.Slots should be specified in Fig. 10.

The problem of holes near bends requires careful consideration because improperlocation can result in distortion and failure of the hole to function as intended.This portion of designing for hole location will be discussed under forming operations.

Limitations -- Limitations of the cutting group of operations include:1. Se~tion of ductile materials requires a minimum tolerance of 10% to 15%

of stock thickness for size and shape of sheared details. Closer

tolerances are obtainable if the first operation is followed byshaving, broaching, boring or reaming.

2. Tolerances on location of details cannot be closer than those onsize and shape and often must be greater.

WTZ/jeg~ C Q~


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Design suggestions tor blanked and punched pam

New sIzeProposed notch

Fit l-A1"'J"Gngement of pGm [or blanking must lHcarefully Bttulied. Nesting or Blight redesign can reducs.crap 108368. (Preued Metal Inatltute)

CORRECT, - - -IL.._~--Blonk

fl' 2-Ftw ~ ~ pa.rl6 Bhotdd k~ to ~ .tnt4gAt edgu em flat blax,b, if""';ble. (P..-ed JUtallDatltute)

\

;;'->

,"

,Fig 3-RedeaiU" CG1lfrequentlll red,," cod...Th6 pcwt belmo 'WO'1'b0 weU Mth6 otMrpGrt ~ requir" cmt-IlidertJblf/ lu8 mat.iGL(Su-)

Notch Is ,.,iiN ~ to b8includl!din"kinkingdi'l\

sr m ax :..t_- I 1 - 2 t m i n~CtlftIHlslH.Jrp If tllldMUIsklls than y,.in.OIIu M. In.(II/owCt1rflM" rodlllB:r"lt

R.1I.f notcHs f D r b " n d1 1 lf JFig 4-Attlmtion to contour details will produce t1 ubest part at the lowest cost. (DtQ1on Rocftllllf~. Co.)

M I n r tJd l4M : hilt IWfIJI fftkbItIu pN">ftlrlWl for highly st1WItI ptIrls

'$Mrp fIfII'1U ~for It W PI ,.,.,,_.,. .F I, 5-Notc1&u m l tJ u h1 l1 . .. .. p w e . , , ' ~ ' ; ' & t b .~ with t1u largeri pouihle. NdlU;l"SWpnotcM. can be UMIdItw pGf"U not tnAbI_,_"to'~conditions. (P....... Metal Institute)


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continued

Laocealine

Foldedlinll

i in. up to 16goge, f in. over 16gaged10 ayTwlc(! metal thicknesst~~('SpaCIng betwllen cuts:fln.up to 16goge.

I ; In . over 16gogeFig 6-Lanud areas must be designed with spacingand depths based em stock thickness. (R. A. W.)o V V

s ; s s s s s s s s s s s s S ) (SSSSSSSSSSSSSI iS$S$SSS$S\SSS9(SSS9 'SSS3

'----iF ~ - - - - roPunchttd Extrud#(/ Pi6rCtld

Fig 7-Holea are punched,extruded Or pierced.Punching does not increasestock thi.ckll.68s" extrudingor piercing increases ef-fective thicknes. at hole.(P~ Metal lrurtitut.,)

Fig 10-S10ts s'hould bedimensioned to shew re-quirements plainly. (PresaedMeta.! Institute)

Punch~SheortJd

SlugHole dia below fhls point is P +10% T

Fig 8-In ]I/l1lching a hole, only part of the metal ishru red by the flunrh: the remainder of the stock istorn out. This causes the hole to taper as indicated.,Pn.'~:-;'t>d : 'o h tn l L n s tit u te )

Punchttd undM'-sirttdandrttdrilledOrilled tllrOCJghonlyDrilled thrOCJghand debur,.,d

Fig 9-Holcs mlLy be punched or drilled, some of thepossible combinations being indicated here. In punching,distance from. the edge will detennine whether distortionoccurs. (Dayton ROJ


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Fonninc operationsBroadly, fcmniDg includes all op-erationa that produce a desired

shape in sheet metal by stressingthe metal beyond its yield point andthus producing a permanent dimen-sional ehange. This includes not onlyh e l l d i n & ' and stamping but also draw-ing, coining, stretch-forminc andsimilar operations. For the ptl1'])08eot this manual, forming operationsare restricted to those that do notmaterially change the thickness ofthe stock; th~ are all bendingoperations.. . . . . . .Belldin& as employed in the stamp-"ing prceeaa, u.ua l1J ' implies bendsalone a straight line rather thanon a CUl'ft. The extent of the bendis designated by the included angleafter bending and the sharpness bythe:radilU at the inside corner. Bendsshould be made across the grain, itpossible, or at 45 deg to the rollingdirection. Bends parallel to the grainshould be avoided. Using the largestpo88l'blebend radius is good practice. becauae this permits greater lati-tude in material selection and oftenusures better bends (Fig 11).

Although minimum bend radiiha" heeD establiahed for som e m a-terials and suggestions are chren inTahJea 1, 2 . 3 and 4y minimumvam. are ~ developed onlyby trial. .A. a !rst approxiJDatkm.Strueer sugpsts multfplyiDg- thestoclt thiekneu (in.) bJ:0.3 to 0.'1 tor soft metall (minatoet thb 0.02 1b.).0.6 to 1.2 for hard metals (minstock thkD 0.06 in.).2.0 to 3.0 for very hard metals.It cracking or tearing oeenrs onbends made with these values, hesuggests trying modifications suchas:1. Increasing the bend radiWJ.2. Barrel fbJ1lhing: the blanb to

remove rough edg:ea before bending.S. .A.mIealing: the blaDka.(. Selecting a more dueti1e mate-

rial.The total length required for bend-ing i8 the sum of the two legs plusthe bend allowance. Depending onthe angle and sharpness of the bend,this length can vary considerably.Caleulations can be made by theformulas given in Fig 12"-

Sometimes costs can be reduced byusing thinner materials than had

Suggested minimum bend radii

TAIt1.a i-AUSTDImC STAJNLKU STEELS

Steel Condition Thidmess R a n g e , in . B e n d BendR ad iu s Angle, d et3 01 , 3 02 , 3 04 Annealed " 1 1 . . . . .. . . . .. . . . .. . . . .. . . . .. . . ~T 18 0

\4 Hard ToO.05O....................... ~T 18 0averO 'OSl. .................... IT 90~ H ard To 1 l . O 5O . . . . . . . . . . . . . . . . . . . . . . , IT 18 00ve r0J l51. .. .... ..... ..... ... , 11 90Hard ToQ .030 ....................... 2T 18 0

0.031 -0.050 .................. : . l~T 90316 Annealed " 1 1 . . . . . . . . . . . . . . . . . . . . . . .. . . . . ~T 18 0

\4 Hard To 0.050 ....................... IT 18 0: OverO.051..................... IT 9 0* Hard To 0.030 ....................... 2T 18 00.031.().050 .................... 3T 9 0Over O.05L .................... 2T 9 0321,347 Annealed " 1 1 . . . . . . . . . . . . . . . . . . . . . .. . . . . . ~T 18 0

Alloy IIId Temper Cond ition110 0-0 . . . . A n n e a I e c I " 0 . 0 1 6 - 0 . 1 2 5 . .1101 ) .H 12 ... " ;( H ard............ 0 . 0 1 6 - 0 . 1 2 5 . 1 1 o o H 1 4 . . . . . * Hard 0 . 0 1 6 - 0 . 1 2 5 . I101 ).H 18 ............ H ard ,.. 0.064, . , .

SNIpSIIarp .Sha 'p1-2T

3 0 0 3 - - 0 ." , . . . . Annealed ... . . . . . . . . 0.016-0.125, . .. .3003-H I2 ;( H ard 0.016 -0..125 ..3003H I4 ~ H ard 0.016 -0.125 .3003-H I8 ......... H ard ............... 0.064 .

ShaIpSharpSharp1~3T

5 0 5 0 - 0 Annealed 0.016 -0.125 .5050-H 32 \4 Hard 0.016 -0.125 ..505O-H34. * Hard 0.016-0.125 ..5050-H38............ H ard 0.064 . ..... ..... .SharpO - l TO - l T1 * 3 T

505Z-O Annealed 0.016 -0..125 .505Z -H 32 ;( Hard 0.016 -0..125 .5052-H34 * Hard 0.016 -0.125 ..5 05 2-H 38 ............ H ard ............... 0.06 4 . ............

SharpO - l T* - 1 * T1-2T

6061-0 Annealed , 0.016 -0.125 .. .6061 -TL H eat Treated 0.064 '"7075-0 Annealed 0.016 -0.032 .7075-T6 H eat Treated 0.064 . O - l T3-ST


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TAIIU J-CARBON AND LOW ALLOY $TI:U.S (In.)

SAE Thickness, in.Steel. . 0.016 0.025 0.035 0.050 0.062 0.109 0.1811020-1025 ............ 0 . 0 3 0.0 3 . 0.06 0.Q6 0.Q6 0.13 0.19107 0-1095 ............. 0.06 0.06 0.09 0.13 0.16 0.31 0.50413 0 ................. 0.03 0.03 0.06 0.ll9 0.1)9 0.16 0.3186 30 ................. 0.03 0.03 0.06 0.09 0.09 0.16 0.31.Annealed.

TABLE 4-COPl'U ALLOYS

Min imum Sui tabl e Radi usNominal o f P un ch, in.Alloy Temper Thickness, in. B end Perp Bend 45 Bend Par.to R oll Dir Deg to to Ro llOi rRoIIOirC o p p e r Ha lf H a rd ........ 0 .02 0 ........... J 1 z Y l2 ~Ex tr a Ha rd . .. .. .. 0 .020 . .. .. .. .. .. } M Y l 2 Y l 2R ed B rass, 85% Draw ing Anneal. . O.oo5-O.ll64 .... Sharp Sharp Sharp

Hal f Hard ........ 0.020..().050.... Sharp Sharp SharpH ar d . . ......... 0.04 0 ........... ~ 1 S t fuExtra Hard ... .. .. 0.040 ........... Y t , fu J S zSpring .......... 0.040........... Y t , ~I !4low B rass, 80% H ard ............ 0.020 ........... Y l2 X. Y t .Sp rin g .......... 0 .0 20 ........... 1 S t ~ * &Car t ridge Brass , 70% Half Hard ... .. .. . O .OOS-O .05 0.... Shar p Sharp SharpH ar d . ........... 0.04 0 ........... ~ Y l2 % 4Ex tr a Ha rd .. .. .. . 0 .0 40 . .. .. .. .. .. Y l2 ~ J S zSp ring ....... '" 0.040 ........... Y t & < l 4 < l 4Ex tr a Spr ing . .. . 0 .0 40 . .. .. .. .. .. ~ < l 4 < l 4Y ellow B rass H alf H ard ........ 0.005-0.090 ..... Sharp Sharp SharpH ar d ............ 0.04 0 ........... Sharp Sharp ~2

Extra Hard ... .. .. 0.040 ........... % 4 ~ * ,S pr ing .......... 0 .04 0 ........... ~ J it < l 4Med ium le ad ed B r ass H a lf H a rd . ....... 0 .04 0 ........... Sharp Sharp SharpP h o s p h o t ' B ron z e, 5% H a l f Har d . ....... 0.0 20-0 .0 70 ..... Sharp Sharp SharpH ar d . ........... 0.04 0 ........... Y t s Y t . %E x t r a Hard ....... 0.040 ........... Y t , % -S pr ing .......... 0 .04 0 . .......... fu - -Phosphor B ron z e, 8% Ha lf H a rd ........ 0.0 05 -0 .06 4 ..... Sharp Sharp SharpH ar d ............ 0.04 0 ........... Y l2 ~ -Ex tr a Ha rd . .. ... . 0 .0 40 . .. .. ... .. . %. ~ < l 4Spring .......... 0.040........... ~ l 4 ~Extra Spring ... .. . 0.064 ........... % z < l 4 < l 4High Silicon Bronze H ar d ............ 0.02 0 ........... Y l2 V 3 2 \ 1 1 ,

S pr in g .......... 0.0 20 ........... ~ fu * &Nick el Silve r 6 51 8 H alf H ard . ....... 0.040 ........... - ~ Y l2H ar d ............ 0.04 0 ........... Y t . Y t . Y t fExtra Hard ... .. .. 0.040........... % ~ isSp rin g .......... 0 .04 0 ........... % z if J S zExtr a Sp rin g . . , .. 0.040 ........... 7 ' 3 2 ~ l 4Nickel S ilve r 55-18 H a lf H a rd ........ 0.0 40 . .......... Y t , \ 1 1 . Y t sHar d ............ 0.040........... Y t , Y J . fuEx tr a Ha rd .. .. .. . 0 .0 40 ... .. .. .. .. ~ ~2 ifSouree: WiZki...... "d Bun...

been considered practical. Use ofreinforcing ribs, flanges or curlededges can often increase the partstrength sufficiently to permit theuse of very thin stock. An exampleis the use of aluminum foil for con-tainers for food products. Bends forribs shouldbe made across the grainif possible; IIllgpsted dimensionsforribs are giVeD inFig 13.Certain preeauti0D8 are requiredin deaigning ftaDges. Length of thebent leg must be adequate to avoiddistortion. Min im lDD height rangesfrom two to four times the stockthickness depending ODsuch factorsas bend radius, material and stockthickness. Tapered flanges shouldDottaper to the fax:e, thus producinga sharp point, but should be cut off80 that the narrowest part is abouttwice the metal thickness. Outsideflanges and flanges around openingsshould also have a height of twicethe metal thickness. Hemmededgesshould be notched at the comers toeliminate gathering dtUing flanging.Design suggestions are given in Fig14 through 17.Holes in bent parts

The location of a hole near a bendmust be planned carefully. Ifa holeis too dose to the bend . distortionwill result and the shape of the holemay be changed enough to preventfunctioning of the part. It is prefer-able to avoid distortion by keepinghole edges at least as far from theinside radius of the bend as twieethe stoek thiekness (see Fig 18). Ifthis is not possible, and the designrequires a hole within the areawhere distortion oeenrs, it can bepunched after bending. This secon-dary operation increases the costconsiderably.Springback

During a forming operation, thecontour of the part matches that ofthe tools, but upon release of theload the part assumes a differentshape becauseof the release of elas-tic stresses. The distortion thatoccurs is called 8pringback Thisdistortion must be taken into ac-count if the final shape is to corre-spond with that of the originaldesign.Saehs states that springbaek isindependent of metal thickness anddepends only on the ratio of bendradius to stock thickness. Spring-back factors for a number of metalsare given in Fig 19.Tools can be designed to compen-sate for springback by causing over-


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Design suggestions lor lormed parts

Fig !1-11I8it:U rodii at bends 8h&u.ld not be less thantM stock fhiekneas; larger radii are desirable.

(F"""""!)fetal Inatitute)

Slng'- 90-~ b#nd. with shorp pcnch(aOl5ln, tnCX rod)L'lI9fh-A +8+0.4f

~J]1,. TSingl. 9O-d~ Hnd with round-noHd punch (0.015In.min rod)L,ngfh A+8+1.!J7(a4f +RJ

Fig 12-Length of etock required for bending atvariOUlJ angles is calqulated as indicated above.

(Str"""".)

- - - - l o o ' t :4f

~'___"_E_L______ ~ f

R=f ~Fig 13-Strengthening ribs ehould be dimensioned asindicated and handled like simple bends. (Stnuoser)

SC O IJo p flong4wherever pcssibklto reduce lII'tIig/lf

KHP flollg# to mlni",u", 10/XVWtIfIt f,orlng of "'lItol

Uf# ;"11 tIIf comtI" only whtlllNllu""~ foroffOCllm#nI

bending of the part. If the partsare being produced from widely usedmetals such as brass, for example,the properties are su1Bciently well-known W make compensation rela-tively easy. However, in workingwith the newer metals, such as tita-nium, springback has been respon-sible for many production difficulties.

TolerancesIn deciding on the tolerances re-quired for a given part. considera-tion must be given to the functionof the stamping, to the product qual-ity (economics permit a high eostitem to be held to closer tolerancesthan an inexpensive one) f to itsmating with other parts, and to

similar considerations. The closerthe tolerance, the greater is the co.tof production. A major factor inkeeping costs in line is to specityclose tolerances only on dimension.that require them for proper func..tioning of the part. For examp l4 l .there is no point in 'specifying do.distance and diameter tolerances Oft

Twic_lMtol thicknessor 0.12 in.min_ j_

!\S\ssssssJl LTwice meta! thicknessor 0.12111.min~.,A

Section A-AFi, lA-Properly designed flanges eliminate troublesin production, (P~ Metal Institute I


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closer tolerances on multislide thanon conventional machines. For ex-ample, formed dimensions can beheld to O.OOI to :t:O.005 in. andangles to Ih to l deg,

Tolerances allowed on hole loca-tions near bends can have a signifi-cant effect on the cost of production.For example, if the tolerance be-

tween the bend and the hole centeris :t:l/64 in. -the hole can be punchedbefore bending, but to hold a toler-ance of :t:0.002 in. would requirepunching after bending with higherdie cost and thus increased cost forthe part.Finish - Specifying unnecessarytolerances on finish also increases

TULE ~SUCCIESTED TOLERANCU ON PUNCHD HOLD IN LOW CAReON STLa

N om in al D iam e te r o f H ole , in.Me ta l Thickness,in. .f- Up to 1 I > 1 u p to 3 > 3 up to 10 > 10 u p to 20 1 >2 0Up to 0.015 . .. .. .. .. .. .. .. .. . 0.0015 0.003 0.004 0.006 0.008> 0 .0 1 5 u p t o 0 .0 31 . .. .. .. ... .. 0.003 0.004 0.005 0.008 0.010>0. 03 1 u p t o 0 .0 62 .. .. .. .. .. .. 0.004 0.005 0.007 0.010 0.015> 0 .0 62 u p t o 0 .1 25 .. .. .. .. .. .. 0.010 0.012 0.015 0.020 0.025>0.125 ...................... 0.020 0.025 0.030 0.035 0.040oTokranees (In.) an plna or mlnu .. Souree: Preued Metal Inatitute.

costs, U the part is not exposedafter assembly, the finish need notbe as good as that on an exposedpart and. as & matter of fact, maybe needed only for protection. Acase in point is an instrument paneltha t was rejected for finish. Exami-nat ion reftaled that ODe aide of thestock had been ateneiled with the:"ame of the producer of the mate-nat Vimn&, this side at an angle,.fter paintinc. it ".. poaible to seethe letters t Ia rouP the eoated sur-(~. To prnHit t .h ia show-throughof the lri.wn, the s ide bad to beftni$h..d at an additional expense.How("~r. thia aide of the panel wasinstalled 00 tIM baa tde of the instru-m..nt and nqainId protection only.In thi. nI..M. rejectioD caused a largemonet&.r7 ... tIIat .... actually notneee.... ry.

stamping manual

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