Die Cast Housings for Battery Packs and Energy Storage
One part, three requirements
A battery or energy storage enclosure is asked to do three jobs at the same time. It carries structural load within the pack, it forms part of the thermal path that moves cell heat to a cooling plate or to the outside air, and it has to satisfy a flame-retardant specification for the application. Our EV battery housing line is specified accordingly: flame-retardant alloys, a high thermal path and AZ91D lightweight construction. Treating any one of those three as an afterthought is usually what forces a redesign late in the programme.
The thermal role is the one most often left implicit. Where the casting acts as a spreader or a base, our heat sink castings are specified in the 72 to 100 W/m·K range, and the face that mates to the cooling plate should be machined rather than left as-cast. Contact resistance across that joint frequently dominates the whole thermal budget, so flatness there is worth specifying alongside the alloy rather than after it.
Flame retardance is a specified standard, not a material property
Flame-retardant behaviour comes from the alloy and, in some designs, from a coating or barrier layer - it is not something that can be inferred from a datasheet written for a different programme. State the standard, the test method and the wall thickness at which it must be met, because a rating established on one section does not automatically carry across to a thinner one. We cast ADC10 and ADC12 aluminium, AZ91D magnesium and Zamak zinc alloys, with custom alloys available per specification.
Magnesium deserves a separate note in this application. AZ91D saves real mass in a pack enclosure, but it is more anodic than the steel or aluminium fasteners around it, so galvanic coupling in a damp environment has to be designed out through isolation or coating. Raising that during DFM costs nothing at all, whereas discovering it during a humidity or salt-spray test costs the tooling and the schedule.
Lightweighting without giving up stiffness
Removing mass from a housing is normally achieved with ribs and local section changes rather than by thinning everything uniformly, because stiffness falls faster than weight when a plate is simply made thinner. Ribs also change how the cavity fills, which is why rib geometry is reviewed against mold-flow simulation during tooling design. Our in-house R&D team runs tooling design, mold-flow simulation and material testing as a single activity for exactly this reason.
Tell us the pack or rack layout, the dissipated power, the flame-retardant standard you have to meet and the annual volume. DFM review is free and we reply within 24 hours, prototype samples ship in about 7 days and volume production runs 30 to 45 days after approval, with ISO 9001, IATF 16949, RoHS and REACH documentation and full batch traceability.
FAQ
Which alloys are used for battery housings?
ADC10 and ADC12 aluminium are standard, with AZ91D magnesium where weight reduction matters and custom alloys per specification. Where a flame-retardant rating is required, please state the standard and test method so the alloy and any coating can be quoted together.
How is the thermal path handled?
Our heat sink castings are specified in the 72 to 100 W/m·K range. In a pack enclosure the face that mates to the cooling plate should be machined on five-axis CNC centres, because joint resistance across that interface often dominates the thermal budget of the finished assembly.
Is magnesium suitable for a battery enclosure?
AZ91D is cast routinely for lightweight construction. It is more anodic than most mating metals, so galvanic isolation or a compatible coating has to be designed into the assembly; raise it during DFM and we will propose a protection route for the specific joint.
What documentation comes with the parts?
Full batch reports, CMM inspection data and material certificates, with inspection reports and PPAP documents available for automotive programmes, all under ISO 9001 and IATF 16949 with RoHS and REACH compliance.
All figures above refer to standard product data sheets; final confirmation is subject to written quotation.