Brass Inserts Manufacturer - Built to Fit, Machined to Hold
We manufacture brass inserts that will work and hold under critical condition. Press-fit, Heat set, molded-in, ultrasonic we have cut thousands of them. Some parts ship to USA, some ship to consumer connectors in Germany and some other may ship to Europe for auto line.
Whether it is a Brass Threaded Insert, Brass Molding Insert, or OEM custom Brass Insert for plastic molding, we cut them with real precision knurl grip, clean thread and tight tolerance. Our inserts are not just good on paper but they work when parts hit the press.
Looking for Brass Inserts that hold and install right the first time?
Request a Free Brass Insert Quote
We serve clients across the USA, UK, Europe, and Asia, supplying tight-tolerance parts that hold up under real world use, not just clean lab conditions. Whether you need 500 piece or 5 million pieces mass production, we are built to deliver.
Why Use Brass Inserts?
Insert is not just shiny threaded part. It is the perfect balance of strength, corrosion resistance, and thermal conductivity. In plastic molding application, it flow better and does not deform under pressure but soft might be. Brass threads stay clean and resist galling. they do not strip the moment someone grabs screwdriver too hard.
Brass Inserts make assemblies stronger and cleaner. Instead of just forcing screws into plastic, you get repeatable torque and reusability. No cracks and stress marks. Just a solid, finished feel.
Materials - What We Machine Daily
We do not run custom brass alloy. We stock and machine known grades, tight batch control.
- C360 - Best for sharp threads, dry machining
- CZ121 - For fine knurling, good chip control
- C385 - Great for molded-in inserts, smoother tool feed
Each grade cuts differently. We have to adjust speed, chip break, and tooling based on grade. In our one batch of PO-145 needed a new knurling insert at mid-batch due to edge wear. cleaned the groove, ran the rest smooth.
Threads - Internal, External, Cleaned Before Ship
- Metric: M2 to M16
- UNC/UNF: 4-40, 6-32, 10-32, 1/4-20
- BSP, NPT available on request
- Through-threaded, blind, closed bottom
- Side-tapped inserts supported
- Tap cleaned, chamfered, light deburr pass on every batch
We once had a batch of 5,0000 pieces with blind M5 threads. First tool chipped after 800. We caught it on the gauge, swapped tools and rechecked depths, and kept thread pitch consistent. This is how it should be work.
Tolerances - What We Actually Hold
We do not write ±0.10 mm and hope. We measure. We track. We scrap if needed.
- OD tolerance: ±0.05–0.10 mm typical
- Thread pitch: Go/No-Go checked every 10 to 15 pcs
- Knurl height: Controlled within ±0.10 mm on press-fit specs
- Roundness: Within 0.05 mm on most diameters
Our factory use micrometers, bore gauge and optical comparators for quality checks. No tolerance is “close enough.” We once had to re-run 5000 inserts when a collet slipped and gave us +0.04 mm on OD. Fixed it, logged it, ran it again. Clean.
Surface Finish & Processing
- Tumbled Finish: Default, clean edge removal
- Brushed Finish: On visible external inserts
- Machined Finish: No post-process, raw from tool
- Nickel Plating, Tin Plating, Gold/Silver: Via certified partners
- Heat Treat & Cleaning: Brass does not need hardening, but we degrease every batch before ship
- Packing: Tray pack, bagged with labels, or foam-boxed for critical threads
One of our client need nickel plated insert with foam separators and we ran full plating, inspected 100%, and tagged each bag with heat lot.
Application Industries We Supply Brass Inserts To
- Injection Mold Builders (USA, Europe)
- Electronics & PCB Assemblers (Germany, South Korea)
- Automotive Plastic Components (UK, India)
- Medical Equipment Makers (USA, EU)
- Consumer Goods (Global)
Recent jobs:
- 440000 Piece for LED panel maker in Denver, USA.
- M6 threaded heat-fit sockets for an Ohio molding house
- 10,000 press-fit inserts for a plastic medical clip run in Belgium
Types of Brass Inserts and Installation Methods
We manufacture brass inserts for all major install types such as press-fit, heat set, ultrasonic and mold-in. Each needs a different outside diameter geometry, knurling and tolerance. If insert will wrong match? We will insert spins, cracks part and pull out. We cut them right so your installation process will run soooth.
Press-In Brass Inserts
- OD Design: Straight wall and slightly tapered
- Knurl Type: Diamond and straight for perfect grip
- Material Fit: Works best for ABS, Nylon, soft PC
- Use Case: Mounting bosses, standoffs, threaded holes in rigid plastic housings
- Risk: Over pressing can crack thin walled parts
We once ran a batch of C360 press-fit inserts with tight knurl height control. Customer in Ohio was cracking ABS housings, turned out their press fixture lacked bottom stop. We sent test fit blocks, adjusted knurl height by 0.05 mm, and solved problem.
Heat-Set Brass Inserts
In these method insert dropped into a pre-molded plastic hole and then pushed in using a heated tool. Plastic softens, flows around the knurl, and re-hardens to lock the insert.
- OD Design: Tapered entry, vented or open-ended
- Knurl Type: Helical or diamond
- Plastic Types: Nylon, ABS, PC, PEEK heat tolerant plastics
- Tooling: Hot-tip soldering iron, thermal press, CNC controlled heater
- Critical Detail: OD taper must match hole ID to avoid float and sink
We machine thousands of heat-set brass inserts monthly. For one batch used in PEEK enclosures in the UK, we ran a 5° entry taper and included a chamfer ring. Held ±0.02 mm on OD for clean install across 8 cavities.
Ultrasonic Brass Inserts
Installation using vibration and pressure. Ultrasonic horn vibrates at high frequency, creating heat from friction between insert and plastic then softens plastic and lets the insert sink in.
- OD Design: Shorter length, precise diameter
- Knurl Type: Spiral or multi-start diamond for grip
- Application: Fast install for mass production
- Risk: Too sharp a knurl, wrong horn can overheat and cause flash marks
- Ideal For: Thin-walled parts, tight spacing, automated assembly
Mold-In Brass Inserts (Pre-Insert and Post-Mold Insert)
Installed during the plastic molding process. Insert is placed into the mold before injection, or post-injected into semi-solid plastic.
- OD Design: Flanged or barbed to resist pull
- Knurl Type: Straight grooves or anchor fins
- Usage: Plastic enclosures, connectors, threaded caps
- Advantages: Zero secondary process, strongest mechanical lock
- Requirement: Mold design must allow accurate insert placement
What Makes Our Inserts Hold Better
- Tool sharpened every 2000 pcs - no drag, no burr
- Knurl depth checked every 50 pcs
- Dry-cut strategy - avoids chip weld on OD
- Fixture torque-tested - We actually press them into test blocks
- Reamed pilot samples - So clients can test fit before main run
- Repeatable batches - Same tools, same feeds, no re-tuning every order
We once tested 5 insert fits across 3 mold cavity types and adjusted knurl height by 0.03 mm for smooth install.
Brass Insert Buyer FAQ
Q1: Can you machine custom insert shapes?
Yes. Oval inserts, vented cores, multi-start threads , we machine per drawing. Send product drawing or 3D step file.
Q2: What is your standard tolerance on brass inserts?
Most inserts are machined to ±0.10 mm OD. Threads are checked to Go/No-Go. Knurls held to fit range based on your plastic type.
Q3: Can you plate and finish the inserts?
Yes. Nickel, tin, gold, silver via trusted vendors. We inspect every lot after plate for burrs and buildup.
Q4: Can you ship to the USA and Europe?
We do it montly. USA clients in Texas, Ohio, California. UK, Germany, and Italy too. Fast air shipment (FEDEX, UPS, and DHL) and sea cargo for large batches.
Q5: Do you supply test samples before full production?
Yes, we can send 5 to 10 piece as a testing samples. We do this often for new tooling and when a customer needs to confirm fit in their mold.
Q6: What is your lead time for brass inserts to the USA or Europe?
For repeat jobs, 15-20 working days is common. New parts with tooling or plating may need 20-25 days. We ship via air for small batches and Sea cargo for high volume.
Why Buyers Stick With Us
- We flag drawing issues. Had a CAD file last month with thread depth wrong, we called, fixed it, saved the batch.
- We re-run when needed. A knurl tool slipped last year. We caught it 300 pcs in. Scrapped and reset.
- We know what matters. Your inserts must go in clean, hold right, and not spin. That is the job.
- We keep our collets, cutters, and fixtures clean. No sloppy work.
- We send photos if something looks off. No guesswork, no delay.
Ready to Get Brass Inserts That Actually Fit?
You are not just buying a part. You are buying a fit that works, first time, every time.
We ship across the USA, UK, Europe, and Asia. Clean threads. Clean fits. No excuses.
