When developing products with limited production runs, choosing the right manufacturing process is crucial. Injection molding, while economical for high volumes, can be prohibitively expensive and slow for low volumes. Enter low volume parts machining – a flexible, cost-effective alternative that empowers designers to bring products to market faster.

What Is Low Volume Parts Machining?

Low volume machining typically refers to producing 50 to 10.000 parts using CNC (Computer Numerical Control) equipment. Unlike injection molding, it requires no custom tooling, making it ideal for pilot runs, bridge production, or customized components. Parts are machined directly from solid blocks or rods, offering unmatched material flexibility and precision.

Why Choose Machining Over Injection Molding?

Injection molding demands expensive steel or aluminum molds costing thousands of dollars and weeks of lead time. For small batches, this cost per part becomes unsustainable. Machining eliminates tooling costs entirely, which translates to lower upfront investment and faster turnaround. Design changes can be implemented instantly by simply updating the CNC program – no new mold required.

Key Advantages of Low Volume Machining

● No tooling costs: Perfect for design iterations and small batches.

● Material variety: Metals (aluminum, steel, titanium), plastics, and composites are readily available.

● Precision: CNC machines hold tight tolerances (±0.005 mm), suitable for functional testing and end-use parts.

● Complexity: 5‑axis machining can produce intricate geometries without assembly. The following images show parts in 5-axis machining.

● Speed: Parts can be machined in days, not weeks. 

When Injection Molding Still Makes Sense

For very high volumes (tens of thousands), the per‑part cost of injection molding drops dramatically. Also, extremely complex plastic parts with undercuts may be easier to mold. But for most low‑volume needs, machining wins on cost, speed, and flexibility.

Cost and Lead Time Comparison

A simple CNC part might cost $50–$200 each for a run of 100. while injection molding would require a $5.000 mold plus $5 per part – totaling $5.500. Machining the same 100 parts could range from $5.000 to $20.000 depending on complexity. The breakeven point varies, but generally under 1.000 parts machining is more economical. 

Lead times for machining are typically 1–3 weeks, compared to 4–8 weeks for injection molding (including mold fabrication).

Design Considerations for Machined Parts

To optimize for low volume machining, keep these principles in mind:

● Avoid deep cavities with small tools: Design for standard tool lengths to reduce cycle time and tool breakage.

● Use radii in internal corners: Sharp corners require specialized tools; adding a radius allows standard end mills.

● Consider wall thickness: Very thin walls may distort during machining; maintain at least 0.5 mm for plastics, 0.8 mm for metals.

● Leverage multi‑axis machining: Reduce setups by designing parts that can be machined in one or two operations. 

Specify tolerances wisely: Tight tolerances increase cost; only call out what is functionally necessary.

How to Choose a Machining Partner

Look for shops with experience in your industry, ISO certifications, and a range of CNC capabilities (3‑axis, 5‑axis, turning, etc.). Ask about their quality control processes, material sourcing, and lead times. Visiting the facility or requesting samples can reveal their capability.

Future of Low Volume Machining

Automation and hybrid processes (combining 3D printing with CNC) are making machining even more accessible. AI‑driven CAM software optimizes toolpaths, reducing cycle times and costs. These trends ensure machining remains the smart choice for low volumes.

Conclusion

For product designers facing low volume production, machining offers a smart, flexible path from prototype to market without the burden of tooling investment. By understanding its strengths and limitations, you can make informed decisions that save time and money. Embrace machining as your go‑to alternative to injection molding.