Equipment mounting brackets
General machine and cabinet brackets that carry a component off a frame, ribbed on the tension side and drilled to a hole pattern rather than machined all over.
Die cast aluminum brackets and mounts
Die Cast Aluminum Brackets and Mounts
A die cast aluminum bracket is a load-bearing mounting part that positions and supports a component, reaching its required stiffness through cast ribs rather than thick walls. CharMax Precision casts brackets, arms, mounts and adapter plates in A380, ADC12 and A360 aluminum from 20 g to 12 kg, with machined datums holding hole positions to ±0.05 mm.
In short
A die cast aluminum bracket is a load-bearing mounting part that positions and supports a component, reaching its required stiffness through cast ribs rather than thick walls. CharMax Precision casts brackets, arms, mounts and adapter plates in A380, ADC12 and A360 aluminum from 20 g to 12 kg, with machined datums holding hole positions to ±0.05 mm.
Brackets are where part consolidation pays best. A welded steel bracket is typically three to six laser-cut or stamped pieces plus a weld fixture, a weld operation, post-weld distortion, a straightening step and a full coating system. One aluminum casting replaces all of it. Above roughly 5,000 parts a year the finished piece price usually lands 30 to 50% below the finished weldment, mass drops by more than half for equal stiffness, and the dimensional scatter of a welded assembly is replaced by the repeatability of a steel die.
The trade is tooling. A die is a one-time cost of 3,000 to 25,000 USD, so a cast bracket program makes sense from roughly 1,000 parts a year upward. Below that, machining the same geometry from billet is cheaper, and our sister CNC operation can produce it on the same drawing until volume justifies the die.
Capability at a glance
| Typical parts | Mounting brackets, support arms, motor mounts, adapter plates, sensor mounts |
|---|---|
| Preferred alloys | A380 general purpose, A360 outdoors or in wash-down |
| Part weight | 20 g to 12 kg per bracket |
| Wall thickness | 2 to 3 mm with 1.5 to 2.4 mm ribs |
| Rib thickness rule | 60 to 80% of the adjoining wall, 1.5 mm minimum |
| As-cast hole position | ±0.2 mm |
| Machined hole position | ±0.05 mm, dowel holes to a reamed H7 fit |
| Machined datum flatness | 0.02 mm per 100 mm |
| Weight versus steel | 35 to 45% of an equivalent steel weldment at equal stiffness |
| Typical finishes | Shot blast, chromate conversion, powder coat |
| Annual volume | 500 to 500,000+ parts |
| Lead times | 25-40 days tooling, 15-25 days production |
What a die cast aluminum bracket is
A bracket exists to hold something in a defined position while carrying the load that thing applies. That makes stiffness, not strength, the usual design driver: a bracket almost never breaks, it deflects, and the component it was locating moves out of position. Cast aluminum suits the job because ribs, gussets and bosses can be placed exactly where the load path needs them at no extra cost per part.
Cast brackets are typically 2 to 3 mm in the walls with ribs 12 to 20 mm deep. That combination is far stiffer than a flat plate of the same mass, because section stiffness rises with the cube of depth while mass rises only linearly. It is also easier to cast than a thick wall, since uniform thin sections solidify evenly and do not trap the shrinkage porosity that a heavy boss or a thick plate does.
What a bracket usually does not need is much machining. A bracket that bolts to a flat frame often needs nothing beyond drilled and tapped holes. Machining is reserved for the cases where the bracket has to locate something precisely, which means a machined datum face, reamed dowel holes and positionally toleranced mounting holes cut in the same setup.
Motor and gearbox mounts
Mounts carrying a rotating assembly, where the pilot diameter and bolt circle are machined to locate the motor and the ribbed body carries torque reaction into the frame.
Sensor and camera mounts
Small brackets holding an optical or measurement device where angular position matters, so the interface face is machined and located by two reamed dowel holes.
Adapter and transition plates
Parts joining two components with different bolt patterns, cast near net shape with both patterns and machined only on the faces that need flatness.
Structural arms and legs
Longer load-carrying members with cast-in weight relief pockets and triangulated ribs, replacing a fabricated tube-and-plate assembly.
Pivot and hinge brackets
Brackets with a bearing or bush seat, where the bore is machined and a steel bushing is pressed in before shipment so the wear surface is not cast aluminum.
Replacing weldments and multi-piece machined assemblies
The strongest commercial argument for a cast bracket is not the piece price of the casting against the piece price of a stamping. It is the removal of an entire assembly. A weldment carries the cost of every cut part, the weld fixture, the welding labour, the distortion that follows welding, the straightening operation, and a coating system that has to protect cut edges and weld spatter as well as flat surfaces.
The weight argument is equally concrete. Aluminum is 2.7 g/cm³ against 7.85 for steel, and although a cast aluminum section has to be thicker for equal stiffness, the net result on a typical bracket is 35 to 45% of the weldment mass. On anything that moves, ships in volume or is lifted by hand during installation, that saving has downstream value beyond the bracket itself.
The honest counterweight is tooling and lead time. A weld fixture costs 1,000 to 4,000 USD and can be ready in two weeks; a production die costs 3,000 to 25,000 USD and takes 25 to 40 days. Below roughly 1,000 brackets a year the weldment or a machined part wins on total cost, and we will say so during the review.
| Factor | Welded steel bracket | Multi-piece machined assembly | Aluminum die casting |
|---|---|---|---|
| Piece count | 3 to 6 parts plus fasteners | 2 to 4 parts plus fasteners | 1 part |
| Operations | Cut, form, weld, straighten, coat | Saw, mill, drill, deburr, assemble | Cast, trim, machine, finish |
| Mass at equal stiffness | 100% baseline | 70 to 80% | 35 to 45% |
| Relative finished piece price | 100% baseline | 150 to 300% | 50 to 70% |
| Tooling investment | Weld fixture, 1,000 to 4,000 USD | Soft jaws and fixtures, under 1,000 USD | Steel die, 3,000 to 25,000 USD |
| Dimensional repeatability | ±0.5 to 1.0 mm with weld distortion | ±0.05 mm, but stacked across joints | ±0.1 mm as-cast, ±0.05 mm machined |
| Corrosion protection | Full coating required, cut edges vulnerable | Coating required on steel | Self-passivating, coating optional |
| Best below | 1,000 parts per year | 500 parts per year | Best above 2,000 parts per year |
These are typical outcomes from consolidation reviews rather than a guarantee. Send the assembly drawing rather than the individual part drawings and we will cost the cast alternative against your current landed price.
Alloy options for die cast brackets and mounts
A380 covers most brackets. At 324 MPa tensile and 159 MPa yield it is the strongest of the four common die casting alloys, it machines better than the others, and it is the cheapest. For a painted indoor bracket there is rarely a reason to specify anything else.
A360 is worth its higher alloy cost when the bracket lives outdoors, in a wash-down area or near salt. Copper is capped at 0.6% against 3 to 4% in A380, which materially improves corrosion life, and A360's 170 MPa yield is the highest of the group, so it takes a permanent set later than A380 under an overload. ADC12 is used when a bracket is broad and thin and the metal has to travel a long way from the gate.
The limit to design around is ductility. All these alloys sit at 2.5 to 3.5% elongation, which is a fraction of what a structural steel offers, so cast aluminum tolerates stress concentrations badly. That is not a reason to avoid it; it is a reason to radius every internal corner and avoid abrupt section changes. High pressure die castings also cannot take a conventional T6 heat treatment, because entrapped gas blisters at solution temperature, so design to as-cast properties.
| Property | A380 | ADC12 | A360 |
|---|---|---|---|
| Ultimate tensile strength | 324 MPa | 310 MPa | 317 MPa |
| Yield strength at 0.2% | 159 MPa | 150 MPa | 170 MPa |
| Elongation in 50 mm | 3.5% | 3.5% | 3.5% |
| Density | 2.74 g/cm³ | 2.70 g/cm³ | 2.63 g/cm³ |
| Corrosion resistance | Fair | Fair | Good |
| Machinability | Very good | Good | Good |
| Relative alloy cost | Lowest | Low | Moderate |
Values are typical as-cast properties measured on separately cast test bars, so design to yield with a safety factor rather than to ultimate strength, and remember that a cast section is not equivalent to a machined billet section of the same size.
How a die cast bracket is manufactured
Bracket tooling is usually the simplest work in the die shop, which is why brackets are often a customer's first casting program. Most brackets draw cleanly out of a two-plate die with no slides at all, and a simple die is a cheap die with a short cycle time and long tool life.
The die designer's real work on a bracket is gate placement and rib layout. Metal has to reach the end of every rib before it freezes, so the gate goes at the heaviest section and the ribs are laid out as flow paths as well as structural members. Ribs that dead-end far from the gate are where cold shuts and short fills appear, and a rib that is 1.2 mm instead of 1.5 mm is where they appear first.
After casting, gates and flash are trimmed and the part is shot blasted. What happens next depends entirely on how the bracket is used. A bracket bolting to a flat frame gets drilled and tapped and ships. A bracket positioning a gearbox or an optical sensor gets a machined datum face, reamed dowel holes and positionally toleranced mounting holes cut in a single setup, because that is the only way the hole-to-datum relationship holds ±0.05 mm.
- Cast: overall form, ribs and gussets, bosses, weight-relief pockets, cable routing clips, cast-in part numbers and orientation marks
- Cast: pilot holes in bosses, plus 0.5 to 1.0 mm of machining stock on any face that will become a datum
- Machined: datum faces to 0.02 mm per 100 mm flatness wherever the bracket locates another component
- Machined: dowel and locating holes to a reamed H7 fit
- Machined: positionally toleranced mounting holes to ±0.05 mm, drilled and tapped in the same setup as the datum face
- Assembly: pressed-in threaded inserts, studs and steel bushings installed in-house before shipment
- Left as-cast: non-functional surfaces, rib flanks and the back face, which keeps machining cost proportional to what the bracket actually has to do
Design considerations for cast brackets and mounts
Ribs instead of thickness
A 2.5 mm wall with a 12 mm deep rib is far stiffer than a 6 mm flat wall and weighs less. Keep ribs at 60 to 80% of the adjoining wall, never below 1.5 mm, with 1 to 2° of draft and a fillet at the root.
Lay ribs along the load
Run ribs on the line between where load enters and where it leaves. A rib set perpendicular to the bending axis contributes almost nothing. Triangulate between a loaded boss and the nearest supported wall instead of ribbing a face uniformly.
Make the load path continuous
Trace metal from the loaded feature to every fixed mounting point, keep the path short, and gusset each corner it turns. Do not ask an unsupported thin web to carry a path that then has to change direction.
Design bosses properly
Raise bolt bosses above the surrounding wall so the fastener seats on a defined pad, and blend them in with radii rather than a step. Core out the centre of any boss above roughly 12 mm diameter, or it becomes a shrinkage site.
Nominate machined datums
Mark a primary datum face and two locating holes on the drawing. Hole positions referenced to a machined datum hold ±0.05 mm. The same holes referenced to an as-cast surface hold ±0.2 mm at best, and that is often the difference between an assembly that fits and one that does not.
Avoid undercuts
A bracket that draws in two directions needs no slides. One side-facing hole or an inward lip can add a slide, several thousand dollars of tooling and seconds of cycle time. Reorient the feature or move it to the parting line if the function allows.
Do not rely on cast threads under load
Tapped holes in A380 hold well for joints assembled once. Where a fastener is torqued repeatedly or carries a high preload, specify a steel threaded insert, a press-in stud or a through-bolt with a washer.
Radius everything internal
With 3.5% elongation, cast aluminum does not redistribute stress the way steel does. Fillet every internal corner at 25 to 50% of the wall thickness, and never leave a sharp step where a rib meets a boss or a wall changes section.
Pocket rather than thin
Remove mass with pockets in low-stress regions instead of thinning the wall globally. Pockets keep the remaining wall uniform, which is what controls porosity, while still taking out the metal that is not carrying load.
Cast, machined or stamped: choosing the right bracket process
Die casting is not automatically the right answer for a bracket, and the honest comparison is worth having before tooling is committed. The deciding variables are annual volume, how three-dimensional the geometry is, whether integral ribs and bosses add value, and how tight the tolerances are across the whole part rather than at a few features.
Volume dominates. Casting tooling is a fixed cost, so the cast piece price falls with volume while a machined piece price stays flat. Stamping has the lowest tooling cost of the three for simple flat geometry, but it cannot produce a rib or a boss, so a stamped bracket needing stiffness turns into a multi-piece welded assembly, which is where casting wins again.
We quote castings, and through our sister CNC operation we quote machined parts, so the comparison you get from us is priced rather than argued. Many customers start a program on machined parts at prototype and low-rate volume and move the same drawing to a die once annual quantities justify it.
| Process | Best when | Limits |
|---|---|---|
| Aluminum die casting | Above 2,000 parts a year, three-dimensional form, integral ribs and bosses, weight matters | Tooling cost and lead time, no T6 heat treatment, 1.5 mm minimum wall |
| CNC machining from billet | Below 500 parts a year, prototypes, tight tolerances across the whole part, T6 properties required | Piece price stays flat with volume, cost rises with material removed |
| Stamping, laser and bend | Flat or single-bend geometry, thin gauge, very high volume, small tooling budget | No integral ribs or bosses, stiffness limited by gauge, often needs a second part |
| Welded steel weldment | Low volume heavy structures, field-repairable parts, very large envelopes | Weld distortion, roughly double the mass for equal stiffness, many operations |
| Gravity or investment casting | Low volume with cast geometry, thick sections, heat treatment required | Rougher surface, wider tolerances, longer cycle, higher piece price at volume |
Break-even points shift with geometry. A bracket with deep ribs and cored pockets favours casting at lower volume than a simple flat plate does, because the machining alternative gets expensive faster.
Industries that buy die cast aluminum brackets
Automotive and EV
Powertrain and accessory mounting brackets, battery module mounts, sensor and camera brackets, supplied with PPAP documentation and IMDS data where the program requires it. Lightweighting is usually the stated reason for the conversion from steel.
Robotics and automation
End effector mounts, axis brackets and machine-frame interface plates, where stiffness-to-weight determines how fast an axis can move without losing position at the tool point.
Industrial equipment and machine building
Motor mounts, guard and panel brackets and conveyor supports, frequently replacing welded steel assemblies as a machine builder moves from prototype volumes to a series build.
Consumer electronics and displays
Display and panel mounting brackets, VESA plates and pivot arms, where cast ribs deliver stiffness in a thin package and the finish is visible to the end user.
Solar, telecoms and infrastructure
Panel and antenna mounting brackets cast in A360 for outdoor corrosion life, with cast-in cable routing and captive hardware to reduce installation labour on site.
Medical equipment
Arm, trolley and instrument mounting brackets with documented traceability, first article inspection packages and smooth cleanable finishes.
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Manufacturing services
Aluminum alloys
Part types
Industries served
Further reading
Same company, different process
Visit our CNC machining site Need machined aluminum parts instead of castings?
Die casting pays for itself above roughly 1,000 parts per year. Below that, or while you are still validating a design, CNC machining from billet is usually the faster and cheaper route. CharMax Precision runs a dedicated aluminum CNC machining operation for exactly that work, so you can prototype machined, then move to casting when volume justifies tooling.
Frequently asked questions
Is a die cast aluminum bracket strong enough to replace a steel bracket?
In most cases yes, provided the bracket is redesigned rather than copied. A380 reaches 324 MPa tensile and 159 MPa yield, which is lower than structural steel, so the cast bracket needs more section depth and ribs to match the original stiffness. Done properly the result is 35 to 45% of the steel mass with equal or better deflection under load. Copying a steel bracket's geometry in aluminum is what fails, not the material.
How much cheaper is a cast bracket than a welded steel bracket?
At 10,000 pieces a year, a consolidated casting typically lands 30 to 50% below the finished, coated cost of an equivalent weldment. Most of that saving comes from removing operations rather than from material: no weld fixture, no welding labour, no post-weld straightening, and a coating system that does not have to cover cut edges and spatter. Below roughly 1,000 pieces a year the weldment is usually still cheaper because of tooling amortisation.
What hole position tolerance can you hold on a cast bracket?
±0.2 mm as-cast and ±0.05 mm machined. To reach the machined figure the drawing has to nominate a datum scheme, because a hole is only as accurate as the surface the fixture locates on. The usual arrangement is a machined primary datum face plus two reamed dowel holes, with all positionally toleranced holes drilled in that same setup so no error stacks between operations.
Can you heat treat a die cast aluminum bracket to T6?
No, and any supplier who says otherwise should be questioned. Gas entrapped during high pressure injection expands at solution treatment temperature and blisters the casting surface. If your calculation depends on T6 properties, the options are more section in the as-cast design, a different casting process such as gravity or investment casting, or machining from heat-treated billet. A T5 stabilisation treatment is possible where dimensional stability rather than strength is the concern.
How thick do the ribs need to be on a cast bracket?
60 to 80% of the adjoining wall thickness, with 1.5 mm as the practical minimum. On a 2.5 mm wall that means ribs of 1.5 to 2.0 mm. Thinner ribs risk incomplete filling at the far end of the flow path; thicker ribs create a local thermal mass that solidifies last and shows as a sink mark on the opposite face. Rib depth, not rib thickness, is what buys stiffness.
At what volume does a cast bracket beat a machined bracket?
Roughly 2,000 parts a year for a typical bracket, and as low as 1,000 where the geometry has deep ribs and cored pockets that would be slow to machine. Below 500 parts a year, machining from billet is almost always cheaper because there is no tooling to amortise. We quote both, so the comparison for your specific geometry is priced rather than estimated.
How much does aluminum die casting tooling cost?
A single-cavity production die for a small to medium part typically runs 3,000 to 12,000 USD. Larger parts, multi-cavity dies and tools with multiple slides range from 12,000 to 25,000 USD or more. Tooling is quoted as a one-time charge, remains dedicated to your part, and is stored and maintained at our facility for the life of the program.
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Get your bracket or weldment costed as one casting
Send the bracket drawing, or the whole assembly drawing if you want a consolidation review. You will get piece pricing, tooling cost and a written DFM report covering rib layout, datum scheme and which holes we would machine.
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