Jig Boring Machine: definition, working principle and applications
Jig Boring Machine is a machine built to position holes accurately, with a thermally stable structure and precision scales. It is used for hole patterns where the position between holes matters more than the hole size. 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, semiconductor is used as the example: cleanliness and surface condition that matter more than the nominal size.
Definition
Jig Boring Machine is a machine built to position holes accurately, with a thermally stable structure and precision scales.
Working principle
The principle is straightforward once the jargon is set aside: material is affected in a controlled way, the result is measured, and the process is adjusted from that measurement. For Jig Boring Machine the control points are table size and positioning accuracy, and everything else follows from them.
What makes it repeatable is not one setting but the order of operations and the way the part is held. CMM for the pattern, bore gauge for the sizes, and the surface condition afterwards is Ra 1.6 µm bored, Ra 0.4 µm with a fine boring head.
Typical parameters
| Specification | Typical value |
|---|---|
| Table size | 800 x 500 mm |
| Positioning accuracy | ±0.002 mm |
| Spindle speed | up to 3,000 rpm |
| Spindle taper | ISO 40 or 50 |
| Measuring system | linear scales with 0.001 mm resolution |
| Thermal control | yes, on modern machines |
Applications
Jig Boring Machine is used for hole patterns where the position between holes matters more than the hole size, and in practice it appears most often in jig plates, mould plates, indexing fixtures, instrument bodies.
How it fits into a machining route
Jig Boring Machine 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: pattern complexity and the number of size changes. 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 for the pattern, bore gauge for the sizes 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 Jig Boring Machine?
±0.005 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 for the pattern, bore gauge for the sizes, with the results recorded so a repeat order can be compared with the first.
What is the most common mistake?
Temperature drift during a long job.
How long does it take and what does it cost?
A realistic cycle is 1 to 4 hours for a plate, and the cost driver is pattern complexity and the number of size changes.
Related capability
If you are specifying Jig Boring Machine 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 Jig Boring Machine in the encyclopedia: Surface Grinding Machine, Cylindrical Grinding Machine, Reaming and Boring. Reading them together gives a fuller picture of how the process, the material and the measurement affect each other.
