Engineering Guide / Small Hole Tolerance
Zinc Die Casting Small Hole Tolerance Control Case Study: 5.95mm vs 5.90mm
Engineering judgement, mold-correction priorities and process checks for a 5.95mm vs 5.90mm two-cavity difference in 88T zinc die casting.
This case uses a two-cavity small-hole measurement difference to explain realistic tolerance control for small zinc alloy die castings. On an 88T die casting machine, a 0.05mm difference between two cavities is not unusually large, but it is already meaningful when the hole is a key assembly dimension.
5.95mmSample size
5.95mmCavity 1 casting
5.90mmCavity 2 casting
0.05mmCavity difference
Tolerance Reality for Small Die Castings
| Material / Control Level | Realistic Production Tolerance | Engineering Meaning |
|---|---|---|
| Zinc alloy small parts | Around ±0.05mm for ordinary stable production | Realistic for normal mass production when the mold, machine and measurement system are stable. |
| Zinc alloy with good control | Around ±0.03mm | Requires better mold precision, stable mold temperature and stricter measurement discipline. |
| Zinc alloy high-precision target | Within ±0.02mm | Difficult. Usually requires high-precision mold inserts, stable thermal control, strict inspection, and sometimes post-machining or 100% sorting. |
| Aluminum alloy small parts | Around ±0.08-±0.15mm for ordinary stable production | Aluminum die casting has greater shrinkage and thermal variation, so long-term ±0.03mm control is difficult. |
Zinc stable production
±0.05mm
Zinc good control
±0.03mm
High precision target
±0.02mm
Case Measurement
| Item | Measured Value | Interpretation |
|---|---|---|
| Sample hole size | 5.95mm | Reference size for comparison. |
| Cavity 1 raw casting | 5.95mm | Matches the sample dimension. |
| Cavity 2 raw casting | 5.90mm | 0.05mm smaller than cavity 1. |
| Cavity difference | 0.05mm | Acceptable for many 88T zinc die casting conditions, but worth correcting if this is a key assembly dimension. |
How to Judge the Cause
1If cavity 1 stays at 5.95mm and cavity 2 stays at 5.90mm, first check cavity-size difference, gate or runner imbalance, and mold-temperature inconsistency.
2If both cavities fluctuate up and down, first check injection parameters, mold-temperature fluctuation, cooling, venting and ejection deformation.
3If cavity 2 is also lighter than cavity 1, the likely cause is insufficient filling or intensification pressure in cavity 2.
Correction Priorities
- Measure at least 30-50 pieces per cavity before cutting steel; separate data by cavity number.
- If the difference is stable, correct cavity 2 insert size or shutoff surface rather than adjusting the whole process.
- Check gate balance, runner pressure loss and local filling sequence if cavity 2 is both smaller and lighter.
- Check mold temperature at both cavities because a local temperature difference can change shrinkage and final hole size.
- Confirm measurement method, gauge repeatability and operator consistency before deciding mold correction amount.
- If the hole is a critical assembly feature, reserve post-machining, reaming or 100% sorting as the control plan.
Conclusion: for an 88T zinc die casting project, holding a 5.95mm small hole around ±0.05mm is realistic. If two cavities must be controlled within 0.02-0.03mm, the work should focus on cavity correction, runner balance and mold-temperature stability, not only machine parameter adjustment.
Need help reviewing small-hole dimensional stability?
Send drawings, cavity measurement data, part weight, die casting parameters and mold-temperature records. XSD can help decide whether to correct the cavity, balance the runner or adjust the process window.
Send Dimension Data工程指南 / 小孔尺寸控制
锌合金压铸小孔尺寸控制案例：5.95mm 与 5.90mm 两穴差异
88T 锌合金压铸中 5.95mm 与 5.90mm 两穴差异的工程判断、修模优先级和工艺排查方法。
这个案例用一个两穴小孔尺寸差来说明锌合金小件压铸的真实公差控制。对于 88T 压铸机来说，两穴差 0.05mm 不算异常大；但如果这个孔是关键装配尺寸，0.05mm 已经值得修模或调整工艺。
5.95mm样品尺寸
5.95mm1 号穴素材
5.90mm2 号穴素材
0.05mm两穴差异
小件压铸公差现实
| 材料 / 控制水平 | 现实量产公差 | 工程含义 |
|---|---|---|
| 锌合金小件 | 普通稳定量产约 ±0.05mm | 模具、机器和测量系统稳定时，这是比较现实的量产水平。 |
| 锌合金控制较好 | 约 ±0.03mm | 需要更好的模具精度、稳定模温和严格测量管理。 |
| 锌合金高精度目标 | 控制在 ±0.02mm 以内 | 难度较高，通常需要高精密模具、稳定热控制、严格检测，甚至后加工或全检分选。 |
| 铝合金小件 | 普通稳定量产约 ±0.08-±0.15mm | 铝合金压铸收缩和热波动更大，长期稳定 ±0.03mm 很难。 |
锌合金普通稳定量产
±0.05mm
锌合金控制较好
±0.03mm
目标高精度控制
±0.02mm
本案例测量数据
| 项目 | 测量值 | 判断 |
|---|---|---|
| 样品孔尺寸 | 5.95mm | 作为对比基准。 |
| 1 号穴素材 | 5.95mm | 与样品尺寸一致。 |
| 2 号穴素材 | 5.90mm | 比 1 号穴小 0.05mm。 |
| 两穴差异 | 0.05mm | 对 88T 锌合金压铸不算异常大；但如果是关键装配孔，已经值得修模或调整工艺。 |
原因判断方法
1如果 1 号穴稳定 5.95、2 号穴稳定 5.90，优先判断为模穴尺寸差、浇口/流道不平衡或模温不一致。
2如果两个穴尺寸都上下波动，优先看压射参数、模温波动、冷却、排气和顶出变形。
3如果 2 号穴重量也比 1 号穴轻，多半是 2 号穴充填或补压不足。
修正优先级
- 修模前至少按穴号分别测量 30-50 件，不能把两个穴的数据混在一起看。
- 如果差异稳定，优先修正 2 号穴镶件尺寸或相关封胶面，而不是整体调工艺。
- 如果 2 号穴尺寸更小且重量更轻，应检查浇口平衡、流道压损和局部充填顺序。
- 检查两个穴的模温差异，因为局部模温不同会改变收缩和最终孔尺寸。
- 修模前确认测量方法、检具重复性和操作员一致性，避免把测量误差当成模具误差。
- 如果该孔是关键装配尺寸，应预留后加工、铰孔或全检分选作为控制方案。
结论：88T 力劲机做 5.95mm 这种锌合金小孔，稳定做到 ±0.05mm 是现实的；如果两穴差要控制到 0.02-0.03mm，需要重点修正模穴、流道平衡和模温，而不是只靠调机参数。