Thin-Wall Die Casting for Optical Module Housings
Why 0.3 mm changes the whole process
At a nominal wall of around 0.3 mm, the metal front solidifies before the cavity is filled unless injection is fast enough and the gas has somewhere to go. Conventional die casting traps air in exactly those thin ribs, so optical module housings are produced with vacuum die casting: the cavity is evacuated before injection so that metal follows the wall instead of compressing trapped gas in front of it.
Three parameters decide the outcome in practice - injection velocity profile, die temperature balance across the cavity, and vent design. Our process runs with vacuum assistance and five-axis CNC finishing afterwards, holding general tolerances to ±0.05 mm where specified.
EMI shielding is a design output, not an add-on
Transceiver housings have to be part of the EMI management of the module. Our optical module housings are specified at better than 40 dB shielding attenuation, which comes from the enclosure being a continuous conductive shell. Every discontinuity - a parting line that does not seat, an unsealed connector window, a porous casting - leaks.
This is why porosity limits belong on the drawing alongside dimensional tolerances. Wall thickness, gate location and where the parting line falls should be decided together with the shielding requirement, not after the tool is cut. We review DFM free of charge and accept STEP, IGES and DXF drawings.
Material and finishing choices
The usual candidates are ADC10 and ADC12 aluminium alloys, chosen for castability in thin sections and dimensional stability, with AZ91D magnesium where weight is the driver and Zamak for small, very precise parts. Where the housing also carries heat away from the optics, our heat sink castings are specified in the 72 to 100 W/m·K range.
Finishing is not cosmetic here. Anodising and powder coating change the surface emissivity and contact conductance of a heat-dissipating housing. Tell us early whether the part dissipates heat, because it shifts both alloy selection and the specified surface treatment. Quality documentation covers ISO 9001, IATF 16949, RoHS and REACH.
FAQ
How thin can you cast a wall?
Optical module housings are routinely produced at around 0.3 mm nominal wall using vacuum-assisted die casting. Whether a given geometry can be filled depends on flow length, gate location and thermal balance; we review this in the DFM stage before any tooling is cut.
What EMI shielding performance do you achieve?
Our optical module housings are specified at better than 40 dB shielding attenuation. Achieving this depends on casting soundness and continuous conductive contact at every joint, so porosity limits and parting line location should be agreed when the drawing is released.
Which alloys are available?
ADC10 and ADC12 aluminium are standard, with AZ91D magnesium where weight reduction matters and Zamak zinc alloys for small high-precision components. Alloy selection should consider thermal requirements, because conductivity varies with the alloy choice.
What are lead time and MOQ?
Prototype samples are delivered in about 7 days and volume production typically runs 30 to 45 days after sample approval. Minimum order quantity starts from 100 pieces. Payment is T/T with 30% deposit, and L/C or PayPal are also accepted.
All figures above refer to standard product data sheets; final confirmation is subject to written quotation.