Keyboard Case Manufacturing Glossary
58 terms, defined the way a machine shop uses them. This is the manufacturing vocabulary, not the hobby vocabulary, so there is nothing here about switches or keycaps.
If a shop uses a word you do not recognise, it is probably here. If it is not, email and we will add it.
Materials
- 6061-T6The default aluminium alloy for keyboard cases. Yields around 276 MPa, machines cleanly, and its silicon content puts a slight grey cast into anodised colour.
- 6063-T5A softer, lower silicon aluminium alloy that anodises brighter and more evenly than 6061, with a film typically 10 to 15 percent thicker. Yields around 214 MPa.
- 7075-T6A high strength aluminium alloy containing zinc and copper. Stiffer than 6061 and considerably harder to anodise consistently, so it is rare on colour led designs.
- A5052A Japanese standard aluminium plate alloy common in keyboard plate drawings. Good flatness and a slightly softer typing sound than 6061.
- Brass C360Free machining brass, roughly three times the density of aluminium. The standard weight material. Patinas unless clear coated or PVD treated.
- Copper C110A heavy, soft copper alloy used for weights and accents. Gummy to machine and it darkens visibly within weeks, so it normally needs a clear coat.
- FR4Woven fibreglass in epoxy resin, the same material PCBs use. A dimensionally stable plate material with a neutral sound. Its dust is abrasive, so many shops subcontract it.
- POMPolyoxymethylene, an engineering plastic used for plates. Low pitched and soft to type on, cheap to cut, and it moves slightly with temperature and humidity.
- TemperThe heat treatment condition of an alloy, written after the alloy number as T5, T6 and so on. Two tempers of the same alloy machine and anodise differently, so always state it.
- BilletA solid block of stock that a part is machined out of. A keyboard top case can start as a 12 kg billet and ship at a little over 1 kg.
Machining
- SetupOne fixturing of a part on a machine. Every additional setup adds a fixture, a set up operation and an alignment risk, and setups drive the price of a machined case more than cutting time does.
- Soft jawsMachinable vice jaws cut to match a specific part so it can be held without marking it. Part of the tooling cost on a cosmetic job.
- FixturePurpose made work holding for one part. Usually quoted as a one time tooling charge, and it should not be charged twice on a repeat run.
- Three axisA mill that moves the cutter in X, Y and Z with the tool always pointing the same way. Enough for most keyboard cases and all plates and weights.
- Five axisA mill that can also tilt and rotate the part under the tool. Costs more per hour and can still be cheaper overall by collapsing several setups into one.
- Cycle timeThe machine time to produce one part once it is set up. Slower finishing passes on cosmetic faces are a real and legitimate part of this number.
- ChatterVibration between tool and part that leaves a visible ripple on the surface and pushes the feature off dimension. The usual failure mode on thin leaf spring arms.
- Witness markA visible line or step left where two toolpaths or two setups meet. It can measure perfectly and still scrap a cosmetic part.
- OverageExtra parts started above the ordered quantity to cover cosmetic scrap. A shop that will not quote an overage has not run cosmetic aluminium at volume.
- First articleThe first part off the machine, measured properly against the drawing before the rest of the run proceeds.
- DFMDesign for manufacture. A review where the shop tells you which features in your model are expensive and why. Ask for it, it is usually free and it is the cheapest money you will save.
Finishing
- Type II anodisingThe standard decorative anodise on keyboard cases. Converts the aluminium surface to a porous oxide, dyes it and seals it. Thin enough that it barely affects dimensions.
- Type III hardcoatA much thicker and harder anodic layer. More wear resistant, but it darkens and mutes most dyes and adds enough thickness to matter on a tight fit.
- Blast gritThe abrasive size used to texture a surface before colour. It decides the feel of the finished part and it changes the apparent colour, so it must be specified as a number rather than as the word matte.
- Dye lotOne batch of anodising dye. Dye depletes as parts are processed, so parts finished later in a lot come out lighter unless the bath is replenished.
- BatchingProcessing parts together in one finishing load. The only reliable way to make a top case and a bottom case match, and it belongs on the purchase order in writing.
- Racking markThe small uncoloured contact point where a part was held during anodising. Unavoidable. Specify where on the part it is allowed to sit.
- SealingThe step that closes the pores of an anodic layer so dye cannot leach out. Hot water sealing lightens the final shade slightly, cold nickel sealing holds it closer.
- E-coatingElectrophoretic coating. An opaque resin film deposited electrically and cured. Reaches whites, pastels and flat blacks that anodising cannot, and builds more thickness.
- CerakoteA sprayed ceramic polymer coating with a wide colour range that works on aluminium, steel and brass alike. Useful when one colour has to cover mixed materials.
- PVDPhysical vapour deposition. A very thin, very hard ceramic film applied in a vacuum chamber, used for gold, bronze and black tones on weights and small parts. It barely affects dimensions.
- Golden sampleOne physically approved part that defines the colour, texture and acceptable defect level for a run. It is the acceptance standard, and it settles arguments that words cannot.
- Cosmetic standardA written definition of acceptable surface quality, including viewing distance, lighting, duration and per zone limits. Without one, flawless is unpriceable and unenforceable.
Case and assembly
- Tray mountThe plate screws onto standoffs machined into the bottom case. The cheapest mount to produce and the most tolerant of dimensional variation.
- Top mountThe plate screws to bosses in the top case, so the top half carries the assembly. Stiff and predictable, and the bosses sit in the most cosmetic part of the case.
- Gasket mountThe plate is held between gasket strips seated on shelves in the case. Shelf depth controls gasket compression, which is most of what a buyer hears in the typing sound.
- Leaf spring mountFlexible arms machined into the case hold the plate. The hardest mount to machine well, because arm thickness sets the spring rate and thin arms chatter.
- Integrated plateThe plate is machined as part of the case. Removes the plate to case fit entirely and carries the highest scrap risk, because a late mistake scraps all the cosmetic work already done.
- Gasket shelfThe machined ledge a gasket strip sits on. Dimension it to the compressed gasket, not to its free thickness, and give it a tighter tolerance than the rest of the case.
- CompressionHow far a gasket is squashed in the assembled board, usually expressed as a percentage of free thickness. Keyboard designs commonly target somewhere around 30 to 50 percent.
- StandoffA machined post in the bottom case that the plate or PCB screws down onto. Its height and position must match the PCB you actually have.
- BossA raised machined feature carrying a tapped hole, used to mount a plate to a top case.
- WeightA block of denser metal, usually brass, fitted inside or under an aluminium case to add mass. The efficient way to make a light metal case feel substantial.
- Switch cutoutThe opening in a plate that a switch clips into. Commonly 13.9 mm or 14.0 mm, and the tolerance around it decides whether switches snap in or fall out.
Drawing and tolerance
- Block toleranceThe general tolerance in a drawing title block that applies wherever nothing tighter is stated. Plus or minus 0.1 mm is a normal default for a machined case.
- Position toleranceA tolerance on where a feature sits relative to a datum, rather than on its size. The right way to specify a screw pattern that has to agree with a PCB.
- DatumThe reference a drawing measures from. Without one, a hole pattern accumulates tolerance across a chain of dimensions and nobody knows which features must agree.
- Tolerance stackThe sum of every tolerance in an assembly chain. Each one can be reasonable on its own while the total is outside anything the designer intended.
- Finishing allowanceDimensional room left for the thickness a coating adds. A pocket is coated on both walls, so it closes by twice the build, and a drawing must say whether dimensions apply before or after finishing.
- FlatnessHow far a surface deviates from a true plane, specified over a stated span. The dimension that matters most on a plate, because cutting a thin part relieves internal stress.
- Cosmetic zoneAn area of a part with its own surface quality requirement. Zoning a case into visible, occasionally visible and hidden is the cheapest way to control finishing cost.
- STEP fileThe universal 3D exchange format. Send one per machined part rather than a single assembly export, because each part goes to programming on its own.
Commercial
- MOQMinimum order quantity. In this niche it is rarely a hard floor, it is the point below which setup and finishing batch costs dominate the unit price. Most keyboard runs sit between 50 and 500.
- Tooling chargeA one time cost for fixtures and soft jaws, quoted separately from the per unit price. On a repeat run of the same case you should not pay it again.
- EXWEx works. The shop makes the goods available at its own premises and the buyer arranges and pays for everything after that. The most common basis for a first quote.
- Interest checkA public post gauging demand before a group buy opens. It sets the quantity you should be asking shops to quote against.
- Group buyA community funded production run. Buyers commit money up front, production starts once a minimum is met, and the published ship date becomes part of the specification.
- Lead feeWhat a shop pays for a matched request on a site like this one. It is paid per request taken, not as a commission on the order that follows.
Now put the words to work
The RFQ template and the drawing callouts page use this vocabulary in the places a shop expects to read it.