In-house tooling · Shenzhen

In-House Mold Making & Overmold Tooling

We design, machine and maintain the molds we run — 3,000+ tooling sets built since 2012. That is why a geometry change is a decision between us, not a renegotiation with a third-party shop.

HKWIRE is a custom cable assembly manufacturer and OEM/ODM supplier in Longgang, Shenzhen. The tool room sits in the same building as the molding floor and the test benches, so a mold correction is a machining job we schedule ourselves.

The overmold is where a cable assembly succeeds or fails

On a custom cable, the connector is usually a purchased part. The overmold is not. It is the only part of the assembly that you, your housing and your end user all touch — and it decides three things no datasheet will tell you.

Strain relief

The taper, length and durometer of the overmold decide where the cable bends and how many times it can bend there. Get the geometry wrong and the conductors fatigue at the connector, not in the middle of the run.

Sealing

An IP67 rating is a property of the overmold-to-jacket bond and the insert-to-housing fit, not of the connector alone. Both are tooling decisions made before steel is cut.

Retention

Whether an insert spins, pulls out or walks loose under vibration is settled by the anti-rotation features and cavity fit we build into the tool.

Cost of change

When the mold is in our toolroom, a revision is a quotation for machining. When it sits in someone else’s shop, it is a new negotiation, a new queue and a new lead time.

What we build in-house

All of the following are designed and machined by our own tooling team. We do not broker mold work out.

Tool type	What it produces	Typical application
Low-pressure injection overmold tools	Connector overmolds, strain-relief boots, screw-lock collars	USB, DC, RJ45, custom connector overmolds
Insert molds	Threaded inserts, captive hardware, panel-mount bezels	Panel mount and flush mount assemblies
Vertical injection tools	Circular connector bodies, M8/M12 overmolds	Sensor and actuator cords, industrial I/O
Sealing and waterproof tools	IP67 / IP68 geometries with jacket bond control	Outdoor, marine and wash-down equipment
High-temperature tools	Silicone and high-temp overmolds	High-temperature and silicone wire harnesses
Prototype and bridge tooling	Low-cavity aluminum tools for pilot runs	Pilot builds before production steel is committed

Seven gates from drawing to production

Tooling lead time is 10 working days from approved mold concept to T1. Prototype samples follow in 3 working days; production runs 14 working days after sample approval.

Requirement and DFM review. We read the drawing against the mating parts and return open questions in writing — before any tooling commitment.

2 working days

Mold concept and split-line proposal. You see where the halves meet, where the gate sits and how the insert is held, and you approve it.

With the quotation

Cavity machining and assembly. Steel selection, electrodes, fit and pre-T1 checks.

10 working days typical

T1 sampling. First articles off the tool with a dimensional report.

3 working days · 1 to 50 pcs

Dimensional and fit check against your drawing and the mating connector.

With T1

Correction and re-sample if anything is out. Geometry changes are quoted against the existing tool.

5 working days per round

Release to production. Process parameters and inspection criteria are fixed and kept under your part reference.

14 working days after approval

The six decisions that decide whether a mold works

These are the questions we answer in the DFM review, and the ones worth asking any supplier who quotes you an overmold.

Split-line placement: Where the two mold halves meet. It is moved away from grip surfaces and away from seal faces, because flash on a sealing surface is a leak path.
Strain-relief geometry: Bend-limiting taper, length and durometer. Set against the cable’s minimum bend radius, not copied from a previous job.
Insert anti-rotation: Knurls, flats and hex features that stop inserts spinning in service. This is what keeps a screw-lock collar from turning when the user tightens it.
Gate and vent position: Where material enters and where air escapes. On long, thin overmolds, a badly placed gate means short shots and burn marks.
Shrink and bond behavior: The overmold material is selected for how it bonds to your jacket material, not for hardness alone. A hard material that does not bond is a seal that fails.
Cavity count: Matched to your annual volume so piece price and tool cost are balanced. Over-cavitating a tool for a 500-pcs-a-year part just buys idle steel.

Materials we mold

Material	Why it is chosen	Typical use
PVC	Lowest cost, good bond, wide hardness range	General-purpose overmolds, strain relief
TPE	Soft touch, flexible at low temperature	Handheld devices, cold-environment cables
TPU	Abrasion and oil resistance, high elasticity	Drag chain, industrial, wearable devices
PP	Chemical resistance, low density	Medical and chemical-exposed assemblies
PA (nylon)	High mechanical strength and temperature resistance	Structural overmolds, insert molding
PUR	Tough, hydrolysis-resistant, good for outdoor	Marine, outdoor and direct-burial builds

Jacket compounds available alongside the overmold: PVC, PUR, TPE, silicone and halogen-free. Material certificates are supplied with traceability to the material lot.

Who owns the mold, and what happens to it

Ownership: Tooling is quoted as a separate line item and belongs to you. It is not amortized into a piece price you cannot see, and there is no rebate scheme to unwind.
Storage and maintenance: We retain and maintain the tool free of charge for 36 months after your last order. Maintenance and refurbishment are our responsibility while it is in our care.
End of life: Expected shot life is stated at quotation for your material and geometry. We tell you when a cavity is approaching end of life — before it affects your parts, not after.
Changes: Geometry changes are quoted against the existing tool. Cavity additions and insert changes are usually far cheaper than starting a new one.
Records: Mold drawings, material lot references and process parameters are kept under your part reference, so a reorder years later matches the original build.

Because the tool is retained under your part reference, repeat runs do not need to be large to be economical: 1 to 50 pcs for prototypes, 500 pcs for production.

What we need from you to quote tooling

Twelve items. Send what you have — a drawing plus a mating connector is often enough to start. We will tell you which of the rest actually affect the quotation.

Drawing of the assembly — STEP / STP preferred; IGES, DWG and PDF accepted
Mating connector part number, or a physical sample
Cable specification: conductor size (we run 32–12 AWG), jacket material, outer diameter
Pinout and wiring schedule
Overmold material and color, or the environment it has to survive
Target IP rating, if any, and the test method you will use
Operating temperature range
Flex or bend requirement: cycles, radius, load
Annual volume and expected order pattern
Target piece price, if you have one — it changes the cavity count we propose
Documentation you need: FAI report, material certificates, test data
Shipping terms: EXW, FOB Shenzhen or CIF

Where tooling shows up in your product

Four of our product families depend entirely on the molds we cut. If your part falls into one of these, the tooling discussion is the project.

01Screw-Lock Molded Cables

Threaded collars and locking overmolds where anti-rotation and pull-out strength are the design.

Tooling questions we get asked

Tooling

Do I own the mold?

Yes. Tooling is quoted as a separate line item and the tool is yours. We hold it, run it and maintain it — we do not claim it against your volume.

How long do you keep the tooling?

36 months free of charge after your last order. If you want it released or transferred, we will discuss it when you ask.

Can you modify a mold you built?

Yes, and that is the point of keeping it in-house. Send the revised geometry; we quote the machining, not a new tool.

What files do you need?

STEP or STP preferred. IGES, DWG and PDF are accepted. A physical sample works too — we can reverse-engineer from a part.

Is there a minimum order for a tooling project?

The tooling itself has no minimum. Prototype runs start at 1 to 50 pcs, production at 500 pcs.

Do you charge for tooling storage?

No. Storage and routine maintenance are free for 36 months from your last order.

Can we run our own tooling in your factory?

Yes. Customer-owned molds are run and maintained on our factory floor, and we work as an OEM and ODM manufacturer and supplier for programs that need tooling held under your name.

How many mold sets have you built?

More than 3,000 tooling sets since 2012, designed, machined and in Longgang, Shenzhen, by the same manufacturer that runs your production.

Send the drawing and the mating connector

We will come back with the split-line proposal, the material recommendation, the tooling cost and the piece price — in one document, before you commit to anything.

REQUEST TOOLING QUOTE

Where the tooling ends up

Tooling is one step in a longer process. Once the mold is proven, the job moves to overmolding, cable assembly and electrical testing. If you are still at the drawing stage, start with build-to-print or prototyping and first article inspection.