How to specify Vertical Machining Centre on a drawing
Vertical Machining Centre is a milling machine with a vertical spindle and an automatic tool changer, run from a single programme. It is used for batch work on prismatic parts where several operations have to run without an operator. This entry explains what it is, what the numbers on a data sheet mean, and what to put on a drawing.
It is written from the point of view of the buyer and the drawing office: the values that are realistic in production, the ones that cost money, and the way the result is verified. Where an industry sets the requirement, food processing is used as the example: surfaces that clean down between production runs.
What belongs on the drawing
A clear drawing for Vertical Machining Centre states the function, the tolerance and the verification, and leaves the route open where the function allows it.
- The feature and its tolerance: ±0.01 mm, applied to the features that locate the part.
- The material and its condition: 6082-T6 aluminium, with the certificate requirement.
- The surface finish: Ra 1.6 µm as milled, called out only where it does something.
- The verification: in-house approval with dimensional reports, and the standard the report is written to.
Mistakes that cost money
- Tool lengths set by eye, which puts the first part out of tolerance, which makes the part more expensive without making it better.
- A fixture that swarf collects in, so the second part sits higher than the first, which makes the part more expensive without making it better.
A workable note
Where a general note is used, say so once in the title block and keep the feature level call outs for the dimensions that matter. Leave a clear chip path so the fixture does not need blowing out between parts
Applications
Vertical Machining Centre is used for batch work on prismatic parts where several operations have to run without an operator, and in practice it appears most often in enclosures, manifolds, bracket families, repeat production parts.
How it fits into a machining route
Vertical Machining Centre is one station in a route rather than the whole of it. The part arrives with the previous operation finished and leaves with the features it is responsible for completed, so the datum and the clamping method are agreed before the first part rather than discovered on it.The route is fixed before the first part is cut, and it is the route rather than the individual setting that holds the result: setups and tool changes, not the metal removal. Where a drawing calls for something the route cannot hold economically, that is raised at quotation rather than after the parts are made.
Standards, documentation and what is issued
The documentation requirement is in-house approval with dimensional reports. Material is supplied against a certificate where the application calls for it, inspection results are recorded with the job, and the records are kept so that a repeat order can be compared with the first instead of being measured from scratch.
CMM or height gauge against the drawing is the verification step. Where a customer format or a standard report is required, it is agreed before the batch starts, because a report written after the event is a report nobody can use.
Frequently asked questions
What tolerance should be specified for Vertical Machining Centre?
±0.01 mm is realistic in production. Tightening it beyond the functional requirement increases cost without improving the part.
Which material is usually used?
6082-T6 aluminium is the usual choice, supplied against in-house approval with dimensional reports.
How is the result verified?
CMM or height gauge against the drawing, with the results recorded so a repeat order can be compared with the first.
What is the most common mistake?
A fixture that swarf collects in, so the second part sits higher than the first.
How long does it take and what does it cost?
A realistic cycle is 10 to 30 minutes depending on the number of faces, and the cost driver is setups and tool changes, not the metal removal.
Related capability
If you are specifying Vertical Machining Centre on a drawing and want a second opinion on the route, send the model and the quantity. The first response is a manufacturability review with the likely risk points and a quotation, so the decision can be made on facts rather than on a price alone.
Machining, inspection and documentation are handled in one place, which is why the dimensional report and the material certificate arrive with the parts rather than after them.
Related entries
These entries sit next to Vertical Machining Centre in the encyclopedia: Cylindrical Grinding Machine, Jig Boring Machine, CNC Milling. Reading them together gives a fuller picture of how the process, the material and the measurement affect each other.
