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All corners of handle bars and panel hardware: Class A Area
Figure 12 Handle bars and panel hardware for Class A and B
1. All exposed corners: Class A Area 2. All exposed corners after opening the cover: Class A Area
Figure 13 Identification of Class A and Class B Areas of Boxes
1.2.3. Requirements for the burr quality of sheet-metal punching parts
Class A Area:
In Class A Area, burrs should be removed and cotton gloves are used for inspection. If there are any fibers remaining on the punching part, it will not be qualified. Class B Area:
Burr height in Class B Areas should be the ultimate value in 0. Suppliers can make various standard samples for comparison according to the ultimate value in 0, or check burr heights with a microscope.
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Table 6 Ultimate value of burr height (Unit: mm)
Tensile strength of materials （Mpa） ＞100～250 ＞250～400 ＞400～630 Material thickness of blanking parts ＞0.4 ～0.7 0.12 0.08 0.05 ＞0.7 ～1.0 0.17 0.13 0.07 ＞1.0 ～1.6 0.25 0.18 0.11 ＞1.6 ～2.5 0.37 0.26 0.16 ＞2.5 ～4.0 0.54 0.37 0.3
Requirements for chamfer after burr removal
Bevels and fillets after burr removal should meet the requirements as shown in 0:
Figure 14 Height of chamfer
1.2.4. Requirements for the Slag of Sheet-Metal Punching Parts
Slag in the process of obtaining parts’ shape and inner holes by melting (e.g. laser or plasma cut) should be removed.
1.2.5. Requirements for Tool Withdrawal Marks on Sheet-Metal Punching Parts
The tool withdrawal mark brought during the punching process is acceptable, but the its height is under
15% of sheet thickness.
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1.3. Tolerance Requirements of Sheet-metal Punching Parts
1.3.1. Statement
1、 Tolerances in drawings, if specified, shall always prevail.
2、 If tolerances are not provided in two-dimensional drawings, add a note specifying \
requirements specified in the DKBA4031 General Specification for Sheet-Metal Punching Parts.\ lists the f and m tolerance levels and values.
1.3.2. Tolerance Levels and Values
Tolerance levels are classified into f and m. f allows lower tolerances than m.
Table 7 Tolerance levels and values
Characteristic Diameter, Distance, or Angle Hole diameter Level f (High Precision) Picture ≤ 63 ±0.10 ±0.10 Level m (Average Precision) 400–1000 N/A > 1000 N/A ≤ 63 63–160 160–400 400–1000 > 1000 ±0.15 ±0.15 ±0.20 ±0.30 N/A N/A 63–160 160–400 ±0.15 ±0.20 Blanking Distance between two holes Distance between a hole and an edge ±0.15 ±0.20 ±0.25 ±0.30 ±0.20 ±0.30 ±0.40 ±0.50 ±0.10 ±0.15 ±0.20 ±0.25 ±0.30 ±0.15 ±0.20 ±0.30 ±0.40 ±0.50 2014-1-3
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Distance between a line and an edge ±0.10 ±0.15 ±0.20 ±0.25 ±0.30 ±0.15 ±0.20 ±0.30 ±0.40 ±0.50 Blanking angle ① ±0°30' ±0°30' ±0°30' N/A N/A ±1.0° ±0°30' ±0°30' N/A N/A
Characteristic Diameter, Distance, or Angle Distance between a hole and a bent flange (one bend) Distance between a bent flange and a flat edge (one bend) Distance between two holes (two bends) 2014-1-3
Level f (High Precision) Picture ≤ 63 63–160 160–400 400–1000 >1000 Level m (Average Precision) ≤ 63 63–160 160–400 400–1000 > 1000 ±0.15 ±0.20 ±0.20 ±0.25 ±0.30 ±0.20 ±0.30 ±0.50 ±0.50 ±0.50 Forming ±0.15 ±0.20 ② ±0.20 ±0.20 ±0.25 ±0.30 ±0.20 ±0.30 ±0.50 ±0.50 ±0.50 ±0.25 ② ±0.25 ② ±0.30 ② ±0.40 ② ±0.25 ±0.30 ±0.50 ±0.50 ±0.75 华为机密，未经许可不得扩散 Huawei Confidential 第39页, 共44页 Page 39 , Total 44
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Characteristic Diameter, Distance, or Angle Distance between two bent flanges (two bends) Level f (High Precision) Picture ≤ 63 ±0.15 Level m (Average Precision) >1000 ±0.30 ≤ 63 63–160 160–400 ±0.25 400–1000 ±0.50 > 1000 63–160 ±0.20 160–400 400–1000 ±0.20 ±0.25 ±0.30 ±0.50 ±0.75 Distance between a flat edge and a bent flange (three bends) ±0.20 ±0.25 ±0.25 ±0.30 ±0.40 ±0.30 ±0.40 ±0.50 ±0.75 ±1.00 Distance between two bent flanges (four bends) ±0.25 ±0.20 ±0.30 ±0.30 ±0.40 ±0.50 ±0.30 ±0.40 ±0.50 ±0.75 ±1.00 Distance between two holes ±0.25 ±0.25 ±0.30 ±0.40 ±0.30 ±0.40 ±0.50 ±0.75 ±1.00 (four bends) ② ② ② ② ②
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