In the world of precision metal components, achieving intricate designs with tight tolerances can be a challenge. Photo Chemical Machining (PCM) offers a unique manufacturing process that eliminates mechanical stress, enabling the production of complex parts with high precision. However, to maximize the benefits of PCM, engineers and designers must apply Design for Manufacturability (DFM) principles.

DFM helps ensure that parts are not only functional but also optimized for efficient, cost-effective production. By integrating DFM into your design process, you can reduce manufacturing costs, improve quality, and accelerate time to market.

What Is Photo Chemical Machining?

PCM, also known as chemical etching, is a subtractive manufacturing process that uses photolithography and chemical etching to remove material from thin metal sheets. It is ideal for producing intricate parts with fine features, tight tolerances, and complex geometries that would be difficult or expensive to achieve with traditional machining methods like stamping, laser cutting, or CNC milling.

PCM offers several advantages, including:

• No mechanical stress or heat-affected zones
• Burr-free and distortion-free parts
• Design flexibility with fine detail capabilities
• Fast prototyping and scalable production

However, like any manufacturing process, PCM has its own design constraints. Applying DFM principles ensures that your parts are optimized for etching, reducing waste and minimizing production challenges.

DFM Considerations for PCM

1. Material Selection

PCM works with a wide range of metals, including:

• Stainless steel (for corrosion resistance and strength)
• Copper and brass (for electrical conductivity)
• Nickel alloys (for high-temperature applications)

Choosing the right material early in the design process ensures compatibility with etching chemistry and maintains desired mechanical properties.

2. Feature Design & Etch Factor

Unlike mechanical machining, PCM etches isotropically, meaning material is removed uniformly in all directions. This results in an etch factor, where the width of an etched feature is affected by the depth of material removal. A typical guideline is:

• Minimum feature size = metal thickness
• Hole diameters should be at least 1.1x material thickness
• Slots and fine features should be designed with gradual transitions to avoid over-etching

By accounting for the etch factor, designers can ensure features remain precise and manufacturable.

3. Tolerances & Undercut Control

PCM can achieve tolerances of ±10% of the metal thickness, but this varies based on material type and feature complexity.  It can also have a significant impact on cost. You may think that tighter tolerances mean a "better" part, but you should ask about reduicng costs by opening tolerances.  It might surprise you.

• Critical features should have relaxed tolerances when possible to simplify production.
• Undercut occurs when chemical etching removes material beneath the resist mask. Designing with undercut compensation—such as widening narrow features—helps maintain accuracy.

4. Masking & Etching Strategy

PCM uses photoresist masking to define which areas will be etched. Proper design considerations include:

• Double-sided etching allows for complex geometries but requires alignment precision.
• Partial etching (step etching) can create variable thickness features but should be designed carefully to avoid over-etching.
• Tab placement can prevent part distortion during etching and handling.

5. Cost & Efficiency Optimization

Applying DFM principles can lead to significant cost savings. Considerations include:

• Nesting multiple parts in a single sheet to maximize material usage.
• Reducing unnecessary fine details that increase etching time and complexity.
• Avoiding deep etches when possible to minimize process variations.

Early collaboration with a PCM specialist ensures your design is optimized for manufacturability before production begins.

Conclusion

Photo Chemical Machining is a powerful process for precision metal components, but achieving optimal results requires careful DFM considerations. By designing with etch factor, material properties, feature tolerances, and process limitations in mind, engineers and designers can create parts that are not only functional but also cost-effective and manufacturable at scale.

Are you working on a project that could benefit from PCM? Contact our team of experts to discuss how DFM can enhance your designs!