TOLLERANCES

T O L E R A N C E S

Center to center dimensions - Center to center tolerances are dependent upon the photo-tool used for masking the part. The center to center tolerance is proportional to the linear distance involved as shown below.

Table 2
C/C Dimensions (inches)	Tolerance
1.0" or less	+ .0002
1.0"- 3.0"	+ .0004
3.0" - 6.0"	+ .0008
6.0" - 10.0" (in)	+ .0008

Table 2. Center to center dimensions

INSIDE CORNER RADIUS AND METAL THICKNESS - The minimum inside corner radius will normally be equal to the thickness of metal. If the metal is .005" then the radius will be .005". An inside radius is shown in Fig. 2.

OUTSIDE CORNER RADIUS AND METAL THICKNESS - The normal radius of a sharp outside corner will be 2/3 the metal thickness. An outside corner radius is shown in Fig. 2. Special adjustments can be made if a sharper corner is required.

Fig. 2. Dimension and tolerance display

EDGE BEVEL AND METAL THICKNESS - A small amount of etching or erosion does occur laterally. In most instances the metal sheets will be sprayed from both sides. The resulting edge profile will resemble the drawing shown in Fig. 3. The bevel "A" should be approximately .1 x thickness (T).

In some applications etching from one side is preferred. In that case "B" will be approximately .4 x thickness (T) as shown in Fig. 3.

Fig. 3. Etched from both sides (A) and one side (B)

Table 3
PROTOTYPE AND SHORT RUNS
Approximate flat size	Thickness, "T " inches
Approximate flat size	0.002	0.005	0.010	0.020	0.040	0.060	0.080

2" x 2"	± .0005	± .0005	± .001	± .0015	± .002	± .004	± .005
8" x 10"	± .001	± .001	± .001	± .002	± .003	± .004	± .006
12" x 18"	± .001	± .002	± .002	± .003	± .004	± .005	± .008

Table 3. Tolerances on prototype and short runs

Table 4
PRODUCTION RUNS
Approximate flat size	Thickness, "T " inches
Approximate flat size	0.002	0.005	0.010	0.020	0.040	0.060	0.080

2" x 2"	± .0005	± .001	± .002	± .004	± .005	± .006	± .007
8" x 10"	± .001	± .001	± .003	± .004	± .005	± .006	± .007
12" x 18"	± .001	± .002	± .004	± .005	± .005	± .007	± .010
18" x 24"	± .002	± .002	± .004	± .005	± .006	± .007	± .015

Table 4. Tolerances on production runs

Table 5
RELATIVE FORMABILITY OF COMMONLY USED METALS
MINIMUM RADIUS FORMABILITY - 90°
Material	Alloy	Temper	Across	Grain Direction 45°	Parallel

Low carbon Cold rolled Steel	No. 1	hard	2.0 x	3.0 x T	flat
	No. 2	1/2 hard	1.0 x T	1.5 x T	1.5 x T
	No. 3	1/4 hard	SB	0.5 x T	1.0 x T
	No. 4	soft	SB	SB	SB
	No. 5	dead soft	SB	SB	SB

Stainless Steel	301/302	annealed	SB	SB	SB
		1/4 hard	SB	0.5 x T	1.0 x T
		1/2 hard	0.5 x T	1.0 x T	1.5 x T
		3/4 hard	1.0 x T	1.5 x T	2.0 x T
		hard	1.5 x T	2.0 x T	3.0 x T

Berylium Copper	25	anneaied	SB	SB	SB
	25	1/4 hard	SB	SB	SB
	25	1/2 hard	0.5 x T	0.7 x T	1.1 x T
	25	hard	1.0 x T	2.0 x T	2.2 x T

Brass	No. 6	annealed	SB	SB	SB
		3/4 hard	SB	SB	SB
		hard	SB	SB	0.5 x T
		x hard	SB	0.5 x T	2.0 x T
		spring	SB	1.0 x T	3.0 x T
		x spring	0.5 x T	1.5 x T	3.5 x T

Phosphor Bronze	Grade A	annealed	SB	SB	SB
		1/2 hard	SB	SB	SB
		hard	SB	SB	1.0 x T
		x hard	SB	0.5 x T	2.5 x T
		spring	SB	1.0 x T	3.0 x T
		x spring	0.5 x T	1.5 x T	3.5 x T
	Grade C	annealed	SB	SB	SB
		1/2 hard	SB	SB	0.5 x T
		hard	SB	0.5 x T	2.0 x T
		x hard	SB	2.0 x T	4.0 x T
		spring	SB	3.5 x T	5.5 x T
		x spring	0.5 x T	4.0 x T	7.5 x T

SB = Sharp Bend . . T = Thickness of material The values shown above are suggested for minimum bend radius. Prototypes shouid be made to insure structural integrity.

BEND RADII Table 5 shows minimum internal bend radii for different type metals. The radii shown are generally accepted throughout the industry, but prototypes should be made to insure structural integrity.