Drawing-Based Custom Manufacturing
Custom CNC Machining for Metal & Plastic Parts
CNC machining removes material from metal or plastic stock to create drawing-defined parts without a dedicated molding tool. Milling produces flat faces, pockets and hole patterns; turning produces rotational features. JUNCHU coordinates the machining, finishing and inspection of housings, brackets, shafts and mating components for prototypes and repeat orders.
Housings · Brackets
Shafts · Plates
PART TYPES
Aluminum · Steel
Engineering Plastics
MATERIAL ROUTES
Finishing · Inspection
Assembly
DOWNSTREAM SUPPORT
Fits · Datums
Finished Dimensions
CRITICAL FEATURES
From Drawing Review to Finished Parts
Machining Routes & Engineering Review
The part shape determines the route. Use milling for prismatic features, turning for rotational geometry and multi-axis access where features extend across several faces.
01
CNC Milling
A rotating cutter creates flat faces, pockets, slots and hole patterns in a fixed workpiece. Typical parts include mounting plates, machined housings, brackets and fixtures. Internal corners retain a cutter radius; deep pockets and thin walls need attention to tool reach and support.
ENGINEERING REVIEW
Review datum strategy, cutter access, internal radii and setup count.
02
CNC Turning
The workpiece rotates while tools create diameters, shoulders, grooves, tapers and threads. Common parts include shafts, bushings, collars and fittings. Bores and outside diameters that locate together should share clear datum and runout requirements.
ENGINEERING REVIEW
Review grip length, concentricity, runout, grooves and thread requirements.
03
Multi-Axis Feature Access
Angled holes, several machined faces and contoured surfaces may benefit from indexed or simultaneous multi-axis machining. Tool access, clamping and datum control determine the suitable route. EDM is a separate option for certain hard-to-cut details in electrically conductive materials; it is not a machining route for ordinary insulating plastics.
ENGINEERING REVIEW
Distinguish multi-axis cutting from EDM; confirm feature access and the inspection method.
Before Manufacturing
What We Review Before Quotation
These requirements determine the process route and the scope confirmed in your quotation.
01
Drawing & Revision
Provide a 3D model and dimensioned drawing with a clearly identified revision.
02
Material & Condition
Specify the alloy or polymer grade, temper and any heat-treatment requirement.
03
Part Geometry
Overall size, deep pockets and thin walls determine access, setups and workholding.
04
Critical Dimensions
Mark functional fits and datums; feasibility is confirmed during drawing review.
05
Threads & Small Features
Identify thread standards, depth and small features that need special tools.
06
Surface & Inspection
Specify roughness on functional faces and inspection records required with the order.
CNC Machining Applications
Typical CNC Parts & Their Key Features
Different components need different controls. The examples below show which features usually drive the machining and inspection plan.
01
Housings
Internal pockets, connector openings and threaded cover interfaces; control wall thickness and the finished cover fit.
02
Brackets
Locating faces and mounting holes; keep critical hole positions related to the assembly datums.
03
Connectors
Mating bores, threads and shoulders; specify seating surfaces, burr control and contact requirements.
04
Shafts
Diameters, grooves and bearing seats; define functional fits and runout relative to the locating axis.
05
End Caps
Closure faces, seal grooves and fastener holes; identify dimensions that must hold after finishing.
06
Mounting Plates
Flat reference surfaces, bolt patterns and pockets; review flatness after material removal.
Match material,
process and finish.
6061 aluminum is often considered for housings and plates;stainless steel for suitable corrosion-resistant components;POM and nylon for selected sliding or insulating parts.Choose the exact grade, condition and finished-part tolerances
before specifying the machining route.
Aluminum Alloys
Stainless Steel
Carbon Steel
Brass & Copper
POM
Nylon
Project-specific plastics
Anodizing · Coating · Plating · Appearance Control
Confirm finish specification, masking, color, surface zones and dimensional
impact during quotation.
Application & Engineering Considerations
Design for tool access and finished-part fit.
A cutter cannot create a perfectly sharp internal corner, and a long slender tool is less rigid than a short one. Add practical internal radii, avoid unnecessary deep pockets and apply close tolerances to functional features. For anodized or coated housings, define whether bores, threads and mating surfaces are checked before or after treatment.
CNC Housing: Features to Specify
- Datum faces and the location of mounting-hole patterns
- Mating bores, thread standards and usable thread depth
- Internal corner radii, pocket depth and minimum wall areas
- Surface roughness on sealing, sliding or locating faces
- Finished dimensions after coating, masking and final deburring
Project Planning
Planning Your CNC Machining Order
Compare the manufacturing route, machining effort and approval scope before committing to a batch.
Prototype or Repeat Production
A machined prototype can help verify interfaces before investing in dedicated tooling. For repeat orders, review stock form, fixture reuse and whether several features can be completed in one setup. A design change after the sample is approved may require revised programming, fixtures and inspection.
What Drives Machining Cost
Material removal, setup count, tool reach and inspection effort all affect the quotation. Deep narrow pockets, very small internal radii and close tolerances on every face can increase machining time. Identify the features that control function so practical alternatives can be discussed without weakening the design.
First-Article Approval
Define which dimensions, threads and mating interfaces must be checked on the first article. Where finishing follows machining, agree which results are recorded before treatment and which are checked afterward. Sample approval covers the agreed drawing and checks; a production sampling plan still needs separate definition.
Prepare for Reorders
Keep the approved drawing revision, material condition, finish reference and inspection requirements together. State the quantity per release as well as expected repeat demand. This helps distinguish one-time programming or fixture work from recurring part costs and reduces ambiguity when a later batch is ordered.
Component images are 3D concept illustrations of representative parts.
Before You Start Your Project
Common Questions
Before an RFQ
Review the information needed for a clear quotation, practical process planning and agreed inspection requirements.
What information should I include in an RFQ?
Send the drawing revision, material and grade, quantity, finish, critical dimensions and target delivery date. STEP or IGES models with a dimensioned PDF are helpful. Photos or sketches can start a discussion when CAD is not ready; they may require additional clarification before quotation.
How do I choose milling, turning or another route?
Rotational parts often suit turning, while pockets and multi-face features often suit milling. Angled surfaces or internal details may need another route. Send the complete geometry so the process can be reviewed around access, setups, tolerances and cost.
How are tolerances and inspection requirements agreed?
Identify the dimensions, fits and datums that affect function. Tolerance feasibility depends on geometry, material, process, finish and measurement access. We confirm critical requirements during drawing review; inspection reports, first-article checks and sampling plans should be specified before the order is placed.
Can finished dimensions be checked after surface treatment?
Identify dimensions that must be met after treatment. Coating build and masking can change fits, threads and contact surfaces, so finished-part requirements should be agreed before machining begins.
What should be confirmed before a repeat machining order?
Keep the approved model and drawing revision together with material condition, finish and inspection requirements. Identify any change in quantity, fit or surface treatment. Agree whether existing programming or fixtures remain suitable and which sample or first-article checks are needed after a revision. Previous approval applies to the recorded configuration and acceptance scope.
Choose the Machining Route Around the Interface
| Model feature | What to review | Useful enquiry input |
|---|---|---|
| Deep pocket or narrow slot | Tool reach, stiffness, corner radius and chip clearance | Show the functional depth and any surfaces that can be relieved. |
| Mating bore or hole pattern | Common datums, setup relationships and measurement access | Supply the mating interface and state the finished fit. |
| Thin wall or broad plate | Clamping, material condition and distortion after removal | Identify functional flatness and surfaces that can accept support. |
| Threaded or finished surface | Thread specification, masking and post-treatment dimensions | Define the thread and whether acceptance is before or after finishing. |
Prioritize critical features
Apply close requirements where function needs them. Review alternatives such as a practical internal radius or a separate inserted component when they can simplify access without changing the intended interface. Feasibility is confirmed against the complete drawing, material and finish.
Use the RFQ checklist to bring these decisions into one controlled enquiry package.
Ready To Start Your Project?
Start With Your Drawings - or Tell Us What You Need
Share drawings, photos or sketches with your quantity, material, finish and target date. We review the available information, clarify technical requirements and confirm quotation timing. Complex or multi-process projects may require additional review.
Discuss confidentiality and NDA requirements before sharing sensitive project files.