CYG Technical Case 002 | Visible Surface Marks After Heat Treatment — How Can the Final Appearance Be Improved?

From surface condition evaluation to a more uniform and brighter final appearance

After heat treatment, the current batch of gear components showed more visible dark marks and surface color variation.

From the customer’s perspective, dimensional and functional requirements are important, but the consistency of the final appearance also affects the overall impression of product quality.

Instead of stopping at an explanation of the surface condition, CHANG YI GEAR (CYG) further evaluated whether a practical appearance-improvement solution could be applied.

Customer Challenge

After heat treatment, the surface of the current batch showed more noticeable dark areas, black marks, and local color variation.

Compared with the previous production batch, the difference in appearance was more obvious, and the customer expected a more stable and consistent final finish.

For CYG, manufacturing is not only about completing a component according to the drawing.

When the actual result differs from the customer’s expectation, we also review the condition and evaluate whether there is a suitable way to improve it.

CYG Assessment

CYG further reviewed and compared the surface condition of the parts and evaluated possible follow-up surface treatment options.

The objective of this case was not to change the original dimensions or functional requirements of the component.

The focus was to identify a practical method to improve the final appearance according to the customer’s expectations.

After evaluation, CYG selected one component for electroless nickel plating as an appearance-improvement solution.

Improvement Solution

After electroless nickel plating, the treated component showed a more uniform and brighter metallic appearance, with improved overall surface consistency.

The purpose of adding this treatment was specifically to improve the final visual appearance.

It was not intended to change the gear accuracy or the original functional requirements of the component.

The confirmed process flow for this case can be summarized as:

Machining
→ Heat Treatment
→ Surface Condition Review
→ Improvement Evaluation
→ Electroless Nickel Plating
→ Customer Confirmation

By comparing the parts from different stages, the difference in surface appearance before and after electroless nickel plating can be clearly observed.

Result & Customer Feedback

After the electroless nickel treatment was completed, CYG provided photos of the improved component to the customer for confirmation.

After reviewing the improved appearance, the customer responded positively:

“Very good.”

This feedback was based on the photos provided by CYG.

Therefore, it should be understood as positive confirmation of the improved appearance and not as final physical acceptance of the completed parts.

What This Case Demonstrates

The key point of this case is not simply that an additional surface treatment was applied.

More importantly, when a manufacturing result does not fully match the customer’s expectation, CYG takes the next step to review the condition, evaluate practical options, and present an improved result for customer confirmation.

For us, manufacturing is not only about producing parts according to drawings.

Communication, technical judgment, and practical problem solving are also important parts of a reliable manufacturing partnership.

CHANG YI GEAR — We Think Further for You.

Have a Similar Manufacturing Requirement?

If your custom gears, gear shafts, or precision transmission components have special requirements related to heat treatment, surface treatment, appearance consistency, or other manufacturing conditions, please send us the available technical information for feasibility review.

You may provide:

• 2D / 3D drawings
• Product photos
• Sample information
• Material requirements
• Quantity
• Accuracy or other technical requirements

CYG will review the actual product conditions and evaluate suitable manufacturing and processing options.

CHANG YI GEAR CO., LTD.
Custom Gears | Gear Shafts | Precision Transmission Components
Email: cygears@cygears.com