Part Type
Custom Machined Aluminum Flanges
When the catalog flange is close but never the part you actually need
A custom aluminum flange gets cut to your exact bolt circle, bore, OD, and thickness when no catalog part lines up, and the same goes for steel and stainless flanges. Have an old one with no drawing? It can be reverse-engineered from the sample. Send a STEP and PDF through the quote form and a real person sends a quote back in 24-48 hours.
Updated June 2026
Why catalog flanges almost never fit
Standard flanges come in fixed sizes built around common pipe schedules and a handful of bolt patterns. The moment your design has a non-standard bolt circle, an odd bore, a thickness the catalog doesn’t stock, or a pilot that has to match a specific housing, the off-the-shelf part stops being an option. That is where a flange cut to your print earns its keep: every dimension is yours, not the closest thing a distributor happens to carry.
These parts blend two processes. The faces, bore, pilot, and any O-ring groove are turned so they run true and concentric, and the bolt pattern is milled and drilled on the same setup logic so the holes land where the mating part expects them. If all you have is an existing flange and no model, the team can measure it and build a drawing, so a worn or obsolete part becomes something you can reorder.
The features that make a flange right
A flange lives or dies on a few details. The bolt circle diameter (BCD) and hole count set how it mates, and the cleanest way to specify the pattern is one BCD dimension plus a position tolerance on the holes, not a grid of individual X-Y dimensions that stack up error. A pilot, register, or spigot diameter is what actually centers the mating part, so it usually wants a tighter tolerance than the bolt holes. Face flatness and parallelism matter wherever the flange seals, and an O-ring groove or a raised face controls where that seal sits.
Hub height and overall thickness drive stiffness and how much thread engagement the bolts get. The single most useful thing on the print is a note about what this flange bolts to: a motor face, a gearbox, a tube end, an instrument port, or a mating standard. Matching to that part is what gets it right the first time. Send the sizes that have to match, and the rest can be designed around them.
Material, finish, and a look before you commit
6061 aluminum is the default flange material: light, easy to cut, corrosion friendly, and happy to anodize. 7075 aluminum steps in when bolt loads or vibration get serious. Stainless handles wet, washdown, and outdoor duty, plain steel earns its place in welded assemblies and weld-prep flanges, and brass shows up on instrument and fluid fittings. Finishes follow the material: anodize for aluminum, passivation for stainless, powder coat or plating for steel, or bare metal for prototypes and weldments.
Before any of it gets cut, the team reviews the files at no charge and flags anything that will bite you: a pilot toleranced too loose to center, a bolt pattern that fouls the seal groove, a wall too thin behind a counterbore. Every flange is inspected against the print before it ships, so the BCD, bore, and flatness are confirmed rather than assumed. One flange or a production run, prototype through repeat batches, it all quotes the same way.
Questions
Before you send a job.
01 Can you match a flange to my existing part if I have no drawing?
Yes. Send the old flange or detailed measurements and it can be reverse-engineered into a proper model and print, then reordered as many times as you need. This is a normal request for worn, obsolete, or undocumented parts. Photos plus a few key dimensions are enough to start the conversation.
02 How should I call out the bolt pattern on the print?
Give one bolt circle diameter (BCD), the number of holes, and a position tolerance on the holes rather than a grid of individual X-Y dimensions. Position tolerance describes how a bolt actually has to drop through both flanges and stacks up less error. Note the hole size and whether each hole is clearance or tapped.
03 What material is best for a flange?
6061 aluminum covers most jobs: light, affordable, and easy to anodize. Move to 7075 aluminum for higher bolt loads, stainless for wet or washdown environments, plain steel for welded assemblies and weld-prep flanges, and brass for instrument and fluid fittings. Tell the team what the flange seals or bolts to and the right pick is usually obvious.
04 Can you machine an O-ring groove or a raised sealing face?
Yes, both are routine. The groove width, depth, and diameter come from the O-ring size and the squeeze you want, so put the O-ring spec or the groove dimensions on the print. Raised faces and flat gasket faces are turned to the flatness the seal needs, and that flatness is checked at inspection before the flange ships.
05 Do you make flanges in steel and stainless, not just aluminum?
Yes. Steel, stainless, brass, and both 6061 and 7075 aluminum are all standard flange materials here. The bolt pattern, pilot, bore, and sealing features are machined the same way regardless of material; the choice mainly changes the finish and the lead time on harder stock.
Related
Where to go next.
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