Industries / Machine tool builders
Large Part Machining for Machine Tool Builders
The parts that carry the accuracy of every other part.
A machine tool base is unusual among heavy parts. Almost none of its tolerances describe the base itself. They describe the relationship between the surfaces that other components mount on, because the spindle will be square to the table only if the column foot was square to the bed first.
That makes sequence matter more here than anywhere. These parts are large, usually cast or heavily welded, and machined to a flatness that is small relative to their length. It is the exact combination that residual stress ruins, which is why the honest route is rough, stress relieve, finish, and sometimes a second settling period before the last passes.
Parts that come through this route
Not an exhaustive list. It is here so you can tell whether your part behaves like these, which is what decides the machine and the sequence.
- Beds and basesFlatness and parallelism on the rail mounting strips, rarely across the whole top face.
- Columns and uprightsSquareness to the bed plane, which sets spindle squareness later in the build.
- Cross rails and bridgesLong spans where straightness over length decides the machine specification.
- Saddles and slidesParallel ways, matched pairs, often finished by scraping after machining.
- Ballscrew and bearing housingsBore position relative to the way surfaces rather than to a corner datum.
- Headstock and tailstock castingsBore alignment over distance, usually the tightest requirement on the machine.
Where this work usually goes
Machine classes that suit the sector. Full typical envelopes and part weights are on the machine class reference.
Gantry or bridge mill
The wide flat faces. The part is clamped once and the bridge travels over it, so the whole surface is cut in one reference frame.
Horizontal boring mill
Bores in uprights and webs that a vertical spindle cannot reach without a right angle head.
A transfer between the two
The most accurate and most expensive route when a part needs both. Say which relationship matters most and let the shop choose.
Materials
Grey cast iron for damping, ductile iron where impact or tensile load rules grey iron out, and fabricated S355 for prototypes and low volume. Iron wins on vibration, fabrication wins on lead time and design changes.
Paperwork this sector expects
- Foundry thermal historyWhether the casting has been aged or normalised. An un-aged casting moves like a weldment.
- Flatness reports with temperatureA flatness number without a recorded temperature is not comparable between two measurements.
- Scraping stockIf hand scraping follows machining, the machining specification should leave defined stock rather than chase a final number.
What to put in the RFQ
On top of the envelope, finished weight, material and tolerance that every heavy part needs, this sector wants these as well.
- Which surfaces are functional and which are structural, marked on the drawing
- Flatness and parallelism callouts with the area they apply to, not the whole face
- Squareness requirements and the datum they refer to
- Whether scraping or in-position machining follows, and how much stock to leave
- Foundry standard and ageing history, for castings
- Whether the part is machined in the orientation it will be used in
Have a part like these?
Send the envelope, the finished weight and the sector. We match it with shops that already work to this paperwork. Reply within 24 business hours.