In precision manufacturing, the biggest challenges are not always complex geometries or expensive materials. Sometimes, a seemingly simple component can become a production bottleneck due to strict tolerance requirements.
This case study shares how the Renjie engineering team successfully solved a difficult flatness issue on a stainless steel component that initially failed quality inspection during production.
The project demonstrates how process optimization, machining strategy adjustments, and engineering experience can turn a high-risk project into a successful delivery.
A customer from the semiconductor equipment industry approached Renjie for a batch of precision mounting plates.
The component appeared relatively simple:
Rectangular shape
Multiple mounting holes
Several precision locating features
However, one specification created a major challenge.
| Specification | Requirement |
|---|---|
| Material | SUS304 Stainless Steel |
| Quantity | 300 Pieces |
| Flatness | ≤0.03 mm |
| Parallelism | ≤0.02 mm |
| Surface Finish | Ra 0.8 |
| Delivery Time | 18 Days |
At first glance, the tolerances seemed achievable.
After all, modern CNC machining centers are capable of much higher precision.
The problem was not machining accuracy.
The problem was material deformation.
The first batch of sample parts was processed according to the standard machining procedure.
The process included:
Rough milling
Semi-finishing
Finishing
Inspection
Dimensional inspection results were excellent.
All critical dimensions passed.
However, when the quality team performed flatness inspection using a granite inspection table, the results revealed a problem.
| Requirement | Actual Result |
|---|---|
| Flatness ≤0.03 mm | 0.08 mm |
| Parallelism ≤0.02 mm | 0.05 mm |
The part exceeded allowable flatness by nearly three times.
Production was immediately stopped.
The engineering team gathered to analyze the problem.
At first, machine accuracy was suspected.
However, laser calibration records showed the CNC machine was operating normally.
Tool wear was checked.
No abnormalities were found.
The team then examined the machining sequence.
After reviewing machining data, a pattern emerged.
The distortion occurred after removing a large amount of material from one side of the component.
This caused internal stress within the stainless steel plate to be released unevenly.
As material was removed, the component gradually warped.
Many engineers underestimate residual stress inside stainless steel.
Raw material may appear perfectly flat before machining.
However, once large amounts of material are removed, internal stress distribution changes.
This often causes:
Warping
Twisting
Bowing
Dimensional instability
For thin stainless steel parts, the effect becomes even more significant.
The team realized that simply improving machine accuracy would not solve the problem.
The machining process itself needed to change.
The engineering team redesigned the process.
Instead of removing all excess material from one side first, they implemented a balanced machining approach.
Rough machine one side
Finish machine one side
Flip part
Machine opposite side
Rough machine both sides equally
Leave uniform stock allowance
Perform stress-relief pause
Finish machine both sides symmetrically
This new approach reduced internal stress concentration.
Another improvement involved introducing a controlled resting period between roughing and finishing.
After rough machining:
Parts were removed from fixtures
Components rested for 24 hours
Natural stress redistribution occurred
This additional step allowed the material to stabilize before finishing operations.
Although it added one day to production, it significantly improved final quality.
The team also discovered that excessive clamping force contributed to distortion.
The original fixture applied pressure at only four points.
During machining, slight deformation occurred.
A new fixture was designed featuring:
Additional support locations
Distributed clamping force
Improved rigidity
This prevented part movement while minimizing stress during cutting.
After implementing all improvements, a second batch was produced.
Results improved dramatically.
| Requirement | Result |
|---|---|
| Flatness ≤0.03 mm | 0.022 mm |
| Parallelism ≤0.02 mm | 0.015 mm |
| Surface Finish Ra 0.8 | Ra 0.6 |
The component now exceeded customer requirements.
With the process validated, full production began.
The results were outstanding.
| Production Metric | Result |
|---|---|
| Parts Produced | 300 |
| Rejected Parts | 0 |
| Delivery Time | 16 Days |
| Acceptance Rate | 100% |
| Customer Complaints | 0 |
The customer later placed additional orders for similar components.
This project reinforced several important manufacturing principles.
Many machining challenges originate from material behavior rather than equipment accuracy.
The machining sequence can have a significant impact on final part quality.
Improper fixturing can introduce deformation that affects precision.
Recognizing stress-related deformation early prevented costly production delays.
Modern CNC equipment is incredibly advanced, but achieving consistent quality still depends on process knowledge and manufacturing experience.
At Renjie, our engineering team continuously analyzes machining challenges and develops optimized solutions for complex production requirements.
Whether the issue involves material deformation, tight tolerances, difficult geometries, or surface finish requirements, our focus is always the same:
Deliver precision parts that meet customer expectations.
Need support for CNC machining, stainless steel manufacturing, or custom precision parts?
👉 Get a Quote:
https://www.renjie-precision.com/contact-us/
👉 Learn More:
https://www.renjie-precision.com/contact-us/
