Smart Home Devices & IoT Parts
We have been molding parts for connected devices since before the category had a name for itself — cases, gears and the internal components that make a smart home product work. We also design and sell our own Garage Smart product line, which changes how we look at a drawing: the parts we mold for customers are the same kind of parts we have to live with after the sale.
That matters most in the places a datasheet does not cover — how a housing behaves when the radio has to pass through it, how a gear train sounds after ten thousand cycles, how a battery door feels on the hundredth open.
What We Mold for Connected Devices
The parts that come up on smart home work fall into four groups, and each one is judged by a different test:
- Enclosures and covers — judged on the outside face and on how the seams close.
- Gears, cams and drive parts — judged on wear, noise and centre distance after shrinkage.
- Control surfaces — knobs, rocker switches, buttons and indicator windows, judged on feel and on light transmission.
- Mounting and interface parts — brackets, wall plates, clips, cable glands, judged on fit to whatever they attach to.
The Antenna Is a Wall-Thickness Problem
The single most common mistake in a connected device housing is treating the radio as an electrical problem. It is a mechanical one. A metal can, a metalized coating, a metal insert or even a metal screw placed over the antenna will cut range, and so will a wall that is too thick or too dense in front of it.
What we ask for at design review is where the antenna sits on the PCB, and which faces of the housing are allowed to be metal-free. From there the wall in front of the antenna can be kept thin and in a resin that lets the signal through — ABS and PC are both fine, but a glass-filled grade or a conductive coating over that area is not.
If the product has to pass an RF test, tell us at quoting. Moving an antenna window after the tool is cut means cutting steel, and it is the kind of change that turns a two-week fix into a two-month one.
Gears and Drive Parts
Plastic gears are where shrinkage stops being a cosmetic issue and starts being a functional one. The centre distance between two molded gears depends on how much each one shrinks, so the tool has to be cut with the shrink allowance for the specific resin, not a generic number. POM and PA are the usual choices; POM holds tolerance and runs quieter against itself, while PA takes more load and more heat but moves with moisture.
Where a gear sits on a metal shaft or carries a metal insert, the hub is the part that fails. We keep enough wall around the insert to carry the torque, and we check the tooth root against the load rather than against the drawing alone. If the drive has to run quietly, say so — noise is decided by tooth profile and by how well the two gears are matched, not by adding lubricant afterwards.
Thin Walls, Snap Fits and Battery Doors
Smart home products get smaller every year, and small parts put the wall in conflict with everything else. A wall thin enough to keep the product compact has less room for a screw boss, a snap hook or a rib, so the design has to decide which features earn their thickness.
Snap fits on a battery door or a sensor cover are cycled many more times than a housing that is assembled once in the factory. That changes the requirement: a snap that holds forever and a snap that opens ten thousand times are different geometries, and the second one needs a living hinge or a separate spring element rather than a thicker hook. Tell us the cycle count you expect, and we will design to it.
Material Choice
We keep 13 engineering resin grades on the floor — ABS, PC, PC+ABS, PA6, PA66, PP, POM, PMMA, HDPE, LDPE, TPE, TPR and TPU. On smart home work the split is usually:
- ABS or PC/ABS — visible housings. Paintable, good finish, adequate for indoor use.
- PC — covers that sit near heat, and any part that has to be clear or translucent.
- PA6 / PA66 — internal frames and brackets that carry load.
- POM — gears, cams and anything that slides or wears.
- TPE / TPU — overmolded grips and gasket features.
If the product needs a flame-retardant grade, give us the standard and the wall thickness it must meet at the start. Switching to an FR grade later changes flow and usually the wall, which means the tool changes too.
Surface, Colour and the Visible Seam
On a device that sits on a shelf in someone’s home, the parting line and the gate mark are part of the product. We agree the cosmetic surface on the drawing — where texture goes, which faces are allowed a gate mark, and where the parting line can sit — before the tool is cut, because those three decisions are expensive to move afterwards.
Two-colour molding, painting, laser marking and pad printing all run here, so a colour or finish decision does not need a second supplier. Where a part needs a soft-touch grip over a rigid shell, the substrate has to be designed with a mechanical interlock for the TPE, not just a clean surface.
Assembly and Test
Four assembly lines handle ultrasonic welding, adhesive bonding, screw and snap assembly, hardware insertion and final packing. For connected devices we can add a functional test station — power-on, pairing, button and indicator check — and inspect every unit against an agreed checklist before it is packed.
Housings, gears and assembly sit in one building in Longgang, Shenzhen. When a fit problem shows up on the line, the person who cut the tool is in the same building as the person who found it.
What We Need to Quote
Send the STEP file, a 2D drawing with the tolerances that matter, the material or flame-retardant requirement, the surface finish, the annual volume, and — for anything with a radio — where the antenna sits and which faces must stay metal-free. If the part has a moving joint or a snap that gets cycled, tell us the cycle count.
Browse appliance and smart home parts we have molded — light housings, rocker switches, knobs, gears and handles.
Send your 3D file for a manufacturability review — we will tell you what we would change and why before anything is quoted.