Why the gap exists

Chinese factories base on GB (Guobiao), but the Japanese market demands three layers: JIS + industry standards + each buyer’s own specs.

5 critical differences

1. Dimension tolerance naming and measurement

JIS: JIS B 0401 grades (f, g, h, etc.) GB: GB/T 1800 grades (IT01–IT18)

Example: JIS h7 and GB IT7 are the same grade, but the actual commonly-used tolerances differ (metric vs imperial legacy).

2. Surface roughness

JIS: JIS B 0601 (Ra, Rz, Ry) GB: GB/T 1031 (Ra), but the calibration basis differs (JIS follows ISO 4287, GB follows ISO 4287 + China-specific adjustments)

Example: Japan buyer asks for “Ra 0.8”, Chinese factory reports “Ra 0.8 achieved” — actual measurement 1.6 μm. Calibration gap.

3. Coating / plating thickness

JIS: JIS H 8504 (plating), JIS K 5600 (paint) GB: GB/T 4956 (plating), GB/T 13452 (paint)

Example: JIS H 8504 mandates XRF measurement, GB/T 4956 allows magnetic methods — same “20 μm” spec, different real numbers.

4. Food-contact safety

JIS: Food Sanitation Act + industry voluntary standards GB: GB 4806.1–4806.11 (food safety national standards)

Example: Melamine tableware for Japan — GB 4806.7 compliant, but JIS-required formaldehyde extraction test must be added before import.

5. EMC

JIS: VCCI + Electrical Appliance and Material Safety Act GB: CCC (China Compulsory Certification)

Example: Wi-Fi module for Japan — China CCC is enough, but Japan 技适 (Giteki) mark is still required to sell.

Summary: 5 steps for Chinese factories to align with JIS

  1. Buy the official JIS standard (from JSA, ¥2,000–¥5,000 each)
  2. Calibrate inspection equipment to JIS (via Japanese calibration bodies)
  3. Raise sampling frequency (GB AQL 4.0 vs JIS buyer AQL 1.0)
  4. Pre-agree the JIS-non-conformance handling flow
  5. Run 100% inspection on the first batch with the JIS buyer present