Wexmar provides custom insert machining for OEMs that need threaded, press-fit or molded-in inserts that catalog parts do not cover. From our shop in Canastota, New York, we produce CNC machined inserts on Swiss-type machines and CNC lathes, with knurls, undercuts, flanges and internal threads held to print. Custom threaded inserts are a natural fit for our lights-out Swiss capacity.
What inserts do and who buys them
An insert puts a durable thread or bearing surface into a softer host material such as plastic, wood, composite or aluminum. The outside form resists pull-out and torque-out, and the inside carries the fastener or pin. Typical buyers include:
- Plastic molders and product OEMs specifying molded-in or heat-set inserts
- Electrical and instrumentation makers needing grounding or mounting inserts
- Medical hardware builders with small stainless inserts
- Furniture, fixture and equipment builders using press-fit or bonded inserts
How our custom insert machining works
Swiss turning
Most inserts are small and made in quantity, so they run on our four Maier MLK-32 Swiss-type machines with FMB bar feeders. Parts up to 32 mm diameter are turned, knurled, drilled, tapped or thread milled and cut off complete in one cycle. The guide bushing keeps the knurl and thread concentric, and the machines can run lights-out. More on our Swiss machining page.
CNC lathes
Larger flanged inserts, hex-body inserts and low-volume runs go to our Mazak and Doosan lathes. Live tooling and Y-axis let us cut hex flats, cross holes and slots without a second setup.
Typical insert materials
- Brass and leaded brass for molded-in and heat-set inserts
- 303 and 316 stainless for corrosion resistance and higher strength
- Aluminum for lightweight assemblies
- Carbon and alloy steel for high-torque applications, often plated or heat treated
- Bronze where the insert also acts as a bearing surface
Critical insert features and how we hold them
- Internal thread: tapped or thread milled and checked with go/no-go gages to class 2B or 3B.
- Knurl form and diameter: straight, diamond or helical knurls are formed or cut to a controlled major diameter so the insert seats consistently in the host.
- Thread to OD concentricity: the thread and outside form are produced in one chucking, keeping the fastener axis true to the insert body.
- Undercuts and grooves: retention grooves are form tooled to hold groove width and depth for pull-out strength.
- Burr-free threads: thread entries are chamfered and deburred so molders do not see flash or cross-threading.
Typical insert tolerances and finishes
| Feature | Typical tolerance | Tighter on request |
|---|---|---|
| Outside or knurl diameter | +/-0.002 in | +/-0.001 in |
| Internal thread | Class 2B | Class 3B |
| Overall length | +/-0.005 in | +/-0.002 in |
| Thread to OD concentricity | 0.003 in TIR | 0.001 in TIR |
| Press-fit pilot diameter | +/-0.0005 in | +/-0.0003 in |
| Surface finish | 63 to 125 Ra | 32 Ra |
These are typical values. We confirm each tolerance against part size and material when we quote.
Choosing an insert design
Molded-in inserts benefit from a sealed or blind end so resin does not flow into the thread, and from a groove between knurl bands to resist pull-out. Heat-set and ultrasonic inserts use a tapered body and a lead-in pilot so they seat straight under heat. Press-fit inserts for aluminum or composite depend on a controlled interference on the pilot diameter. If you are converting from a catalog insert, we can machine to the same envelope with a different thread, length or material and hold the same host-hole dimensions.
Secondary operations
Zinc, nickel and tin plating, black oxide, passivation of stainless inserts and heat treat of steel inserts are completed through qualified outside processors. We schedule the outside work and check parts on return, so you receive finished inserts ready for molding or assembly.
Quantity patterns
Inserts are usually a volume part. Typical orders range from a few hundred for a pilot build to tens of thousands per release on blanket agreements. Our bar-fed Swiss machines, lights-out running and second shift keep unit cost practical, and bar stock can be held for scheduled releases. Related sibling parts include threaded components and custom fasteners.
Inspection
Thread gages, pin gages and the Mitsubishi optical comparator handle in-process checks of thread, knurl and groove profiles. Our Brown and Sharpe CMMs support first article work. FAI in AS9102 format, material certs and heat-lot traceability are available.
Getting a quote
Send the insert drawing, host material, thread callout and annual volume. You can upload a drawing for an instant estimate in PDF or STEP, and an estimator will confirm the price. Call (315) 400-2654 with questions on knurl or thread selection.