When a Sheet Metal Part Also Needs CNC or Casting: Combining Processes in One Order

By Jessica Cui · Reviewed by Matthew Wu · Last updated 2026-09-20

Many parts start as sheet metal and finish somewhere else. A bracket needs machined faces. A housing needs a cast corner. Splitting these steps across vendors adds cost and risk.

Xinjiuxinji runs sheet metal fabrication as our main line. CNC machining and casting support it under the same roof. Our Nanpi production base was built in 1999 and holds ISO 9001:2015 certification.

Why Parts Need Combined Processes

Design requirements push parts across process boundaries.

• Machined faces for sealing and mating.
• Threaded holes in formed sheet.
• Cast corners where forming cannot reach.
• Heat-treated or coated surfaces after forming.

Multi process metal parts work best with one responsible supplier. Tolerances transfer cleanly between steps, and nobody blames the other vendor.

Common Process Combinations

When to Add CNC Machining

Add machining when forming cannot hold the feature.

• Flatness or parallelism on a mating face.
• Precise hole patterns and counterbores.
• Threads that must survive assembly torque.
• Features on thick sections after welding.

Our factory runs five CNC machines, including two five-axis centers. Machining after forming happens in the same production flow, so parts do not travel between suppliers.

When to Add Casting

Choose casting for shapes that forming cannot produce.

• Deep three-dimensional curves.
• Thicker walls with internal ribs.
• Low-to-medium volume complex bodies.
• Parts that later need machined interfaces.

We handle aluminum, zinc and iron casting, then machine critical features to drawing. Cast-then-machine is one order, one quality record.

The Cost and Risk Case for One Supplier

Splitting processes across vendors creates hidden costs.

• Extra freight and packaging between vendors.
• Tolerance disputes at the hand-off point.
• Longer total lead time and weaker accountability.
• Repeated quality inspections at each stage.

Multi process metal parts solve this with one drawing, one order and one inspection standard. Our base runs 40 stamping presses from 80 to 400 tons. Two 6 kW laser cutters, five CNC machines and full welding lines complete the chain.

How We Combine Processes in Practice

1. Engineering review maps each feature to the right process.
2. Stamping, deep drawing or laser cutting forms the base shape.
3. Welding joins sub-assemblies where needed.
4. CNC machining completes tight features.
5. Surface treatment and inspection finish the part.

The factory employs 120+ people, including 19 engineers. Since the base opened in 1999, over 70,000 full-process projects have shipped to overseas buyers.

FAQ

Q: Can one order include sheet metal work and CNC machining? A: Yes. Combining processes in one factory keeps tolerances and delivery under one schedule.

Q: Is casting suitable for small volumes? A: Yes, with the right tooling approach. Casting becomes economical when shapes are complex and quantities are moderate.

Q: Do I need separate drawings for each process? A: One master drawing with clear process notes usually works. We confirm the process plan before production.

Q: How does combining processes affect lead time? A: It usually shortens total lead time by removing hand-offs between vendors. Every quotation states a confirmed schedule.