Custom Plastic Enclosures —
From Drawing to
Flame-Retardant Production
From your enclosure drawing to UL94V-0 production parts, matched to your real volume. We run the mold shop and the injection floor under one roof, so the engineer who quotes your part is the one who builds it. CNC and vacuum casting for prototypes; plastic enclosure injection molding with pull-proof brass inserts for production.
- ✓20+ years technician-led; founder degreed in mold design and manufacturing
- ✓40 injection machines, 90–400T, robot-loaded for 24-hour runs
- ✓In-house FANUC CNC and SODICK mirror EDM
- ✓CMM dimensional reports, ISO 9001
- ✓Knurled brass inserts molded into screw bosses
What Is Custom Plastic Enclosure Manufacturing?
Custom plastic enclosure manufacturing turns your housing design into molded production parts, using tooling built to your geometry instead of an off-the-shelf box. The shape is rarely the hard part. The details decide whether the enclosure survives assembly, sealing, and years of field use.
We've built these housings for POS terminals, power outlets, and industrial boxes, so the failure modes below aren't theory to us.
The Real Challenges Engineers Face
Brass inserts spin or pull out; bosses crack
Inserts seated without knurling or correct hole geometry
Sink marks and warp break the seal line
Uneven wall thickness, no draft control before steel is cut
You outgrow your prototype shop at production volume
The shop can't move to hardened tooling, forcing a re-source
How We Solve Them
Pull-proof bosses
CNC-machined brass inserts, knurled and molded in, so they don't spin or lift.
Stable walls
DFM and Moldflow flag thickness and draft before any steel is cut.
One factory across volumes
CNC and vacuum casting early, injection tooling for volume.
The range of parts this applies to is wider than most buyers expect.
Enclosures We Manufacture
We tool and mold custom plastic enclosures across consumer, industrial, and packaging applications. Each category below reflects parts we've actually built.
Power strips & socket enclosures
Surge boards, wall outlets, extension units
POS terminal housings
Payment devices with tight tolerances and EMI-aware layouts
Electronic device housings
Handheld, PCB, and instrument enclosures
Home appliance housings
Small-appliance and white-goods covers
Industrial & electrical boxes
Control enclosures and large machine covers
Daily-use product housings
High-volume consumer parts
Most of these are custom electronic enclosure builds where the screw bosses carry threaded brass inserts. That single detail separates a reliable housing from a warranty return — and it's where we put our deepest engineering.
Brass Insert Molding for Pull-Proof Bosses
Most electronic enclosures fail at the corner bosses, where screws thread into brass inserts. If the insert spins or pulls out, the housing is scrap. Brass insert injection molding solves this only when the insert and the mold are built to work together.
Custom CNC Brass Inserts & Knurling
We CNC-machine custom brass inserts and add knurling and thread profiles tuned to your boss diameter and resin. The knurl bites into the molten plastic, so the cured boss grips on every axis:
- ▸Diamond knurl resists rotation (spin-out).
- ▸Annular grooves resist axial pull-out.
- ▸Thread size matched to your fastener and torque spec.
In-Mold Insert Placement
Inserts are set in the cavity before the shot, so plastic flows around and locks them in a single cycle — a stronger hold than press-fit or heat-staking after molding. We place them two ways:
- ▸Manual loading for prototype and low-volume runs.
- ▸Robot loading for repeatable production output.
This is the same insert molding enclosure method we run for consumer-electronics housings with brass bosses at all four corners. From ten prototypes to a hundred thousand parts, the boss locks the same way. What changes is the process around it.
Worried your bosses will spin or pull out? Send us your boss design and fastener spec, and we'll show you the knurl and insert geometry that locks it in.
Volume-Matched Manufacturing
Injection tooling rarely pays off below a few hundred units. We match the process to your stage, so you scale without switching suppliers.
Prototype & Low Volume: CNC + Vacuum Casting
- ▸CNC machining from solid PC or ABS for functional, dimensionally accurate parts.
- ▸Vacuum casting for short runs of 10–50 cosmetic enclosures from a silicone mold.
- ▸Screw-in inserts while the design is still moving.
This confirms fit, sealing, and assembly before you commit to steel.
Production: Plastic Enclosure Injection Molding
- ▸In-house presses run robot-loaded, around the clock, for 24-hour output.
- ▸Partner capacity from 450T to 3300T for large industrial covers.
- ▸Two-color and gas-assist tooling for multi-material and hollow-section parts.
Low-volume enclosure manufacturing and full production stay under one roof, on one set of drawings. The resin you lock in here decides whether the enclosure passes its flame test.
Materials & UL94V-0 Flame Rating
Electronic enclosures usually need a flame rating, so resin choice is a compliance decision, not a cosmetic one. We mold three resins for enclosure work:
ABS
Cost-effective, good impact strength for indoor electronics.
PC
High impact and heat resistance for demanding housings.
PC+ABS
A tough, processable PC ABS enclosure resin for larger parts.
UL94V-0 Flame Retardant
For electronics we run flame-retardant grades up to UL94V-0, the rating most control and power housings require. Every production lot ships with a material certificate tied to the resin grade and batch, so the spec on your drawing matches the pellets in the barrel. That record stays traceable for the life of the part.
Material control is only half the story; the other half is proving the part measures what the drawing says.
Our Quality & Documentation System
You can't audit a part you can't measure, so documentation is built into every program from quote to shipment. Nothing ships on a verbal "it looks good."
Documentation you receive:
- ▸Preliminary DFM at quote — moldability, wall thickness, and insert-boss risk flagged before you order.
- ▸Full DFM after PO, with Moldflow on complex or thin-wall geometry.
- ▸Trial (T1) report with first-shot results and dimensional checks.
- ▸CMM dimensional report measured against your drawing.
- ▸Material certificate plus a traceable record for every lot.
Inspection equipment behind those reports:
- ▸FANUC CNC and SODICK mirror EDM for tooling accuracy.
- ▸CMM, optical projector, and hardness testing.
- ▸Plug, pin, thread, and go/no-go gauges for in-process checks.
As a custom plastic enclosure manufacturer, we treat documentation as part of the part. Drawings and reports stay under NDA and on file for the life of the tool, so a question six months out has an answer, not a guess. These systems show up most clearly in the programs we've already run.
Want the full documentation trail before you commit? Send your enclosure drawing and talk directly with the engineer who would run your tooling.
Enclosure Mold Case Studies
Six builds that show how we match steel, cavity layout, and process to the part. Customer names and exact volumes stay under NDA.
Case 1 — Consumer Electronics
Corner bosses pulled out under repeated screw torque during testing.
Knurled, CNC-machined brass inserts placed by robot and molded in; boss geometry revised in DFM before steel was cut.
Bosses held through assembly cycling with no insert spin or lift.
Case 2 — Power Outlet Enclosure
A long-run program needed consistent parts past heavy cycle counts without tool wear shifting dimensions.
H13 hardened tooling rated for 500k+ cycles, with balanced cooling for cavity-to-cavity uniformity.
Stable dimensions across all four cavities deep into the production run.
Case 3 — Industrial Control Box
Warpage on large flat faces broke the seal line.
Moldflow-driven gate relocation and 1.2343 hot-work steel for thermal stability across the large surface.
Flat faces held to the drawing, with the seal line closing as designed.
Case 4 — Medical Device Internal Component
A high-volume program on a wear-prone resin, run in a humid environment with corrosion risk.
S136 corrosion-resistant stainless for tool longevity; CMM verification against the drawing on first article and in production.
Stable dimensions at volume, with a full CMM report on every lot.
Case 5 — Prototype Enclosure
Field samples were needed for fit and assembly checks before committing to steel.
CNC machining plus vacuum casting from a silicone mold, with screw-in inserts standing in for molded-in.
Functional units delivered for validation, then carried into injection tooling on the same drawings.
Case 6 — Large Industrial Cover
Shot size and part footprint exceeded our in-house tonnage.
Production moved to an 800T machine on our long-term partner line, with KTM holding tooling and quality control.
Oversized cover molded to spec without splitting the program across two suppliers.
Choosing the right mold steel for the enclosure is half the job; the other half is who stands behind it when something needs a change.
Why OEMs Choose KTM
You're not buying a box. You're buying a supplier who lowers your risk over years, not over one quote.
Technical founder on the floor
Degreed in mold design and manufacturing, 20+ years solving tooling problems hands-on.
Engineer-to-engineer communication
Your contact understands draft angles, gate locations, and shrink, so nothing gets lost in translation.
Time-zone overlap
Our project team works until 20:00 China time to align with US and EU hours, so a Monday question doesn't wait until Wednesday.
Transparent pricing
The quote you approve is the price you pay; no mid-project surprises.
That's why several customers have stayed with us past 10 and 15 years. The questions you're still weighing are answered below.
Custom Plastic
Enclosures FAQ
PC, ABS, and PC+ABS cover most electronic housings. PC handles impact and heat, ABS suits cost-sensitive indoor parts, and PC+ABS balances both. Electronic enclosures run flame-retardant grades up to UL94V-0.
Send Your Enclosure Drawing
Get a free preliminary DFM on your custom plastic enclosure. No hidden fees, no mid-project price changes.