Horizontal Machining Centre vs Jig Boring Machine: which one fits your part
Horizontal Machining Centre is a milling machine with a horizontal spindle and a rotary table, usually with pallet exchange. It is used for parts that need work on several faces in one setup, and for unattended running. 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.
The short answer
Horizontal Machining Centre and Jig Boring Machine overlap, but they are not interchangeable. Choose Horizontal Machining Centre when the requirement is parts that need work on several faces in one setup, and for unattended running; choose Jig Boring Machine when the requirement is hole patterns where the position between holes matters more than the hole size.
Side by side
| Point of comparison | Horizontal Machining Centre | Jig Boring Machine |
|---|---|---|
| What it is | a milling machine with a horizontal spindle and a rotary table, usually with pallet exchange | a machine built to position holes accurately, with a thermally stable structure and precision scales |
| Used for | parts that need work on several faces in one setup, and for unattended running | hole patterns where the position between holes matters more than the hole size |
| Typical tolerance | ±0.01 mm | ±0.005 mm |
| Surface finish | Ra 1.6 µm as milled | Ra 1.6 µm bored, Ra 0.4 µm with a fine boring head |
| Cost driver | pallet utilisation, because an idle pallet is still a cost | pattern complexity and the number of size changes |
Which one fits your part
Work from the feature that has to work. If the requirement is parts that need work on several faces in one setup, and for unattended running, Horizontal Machining Centre is the safer call; if it is hole patterns where the position between holes matters more than the hole size, Jig Boring Machine wins on cost or on lead time. Where the drawing does not make it clear, that is the question to settle before quotation rather than after.
A note on specification
Write the drawing so that either route can be considered where the function allows. That keeps the quotation competitive and stops a process being specified where a result should have been.
Applications
Horizontal Machining Centre is used for parts that need work on several faces in one setup, and for unattended running, and in practice it appears most often in gearbox housings, pump bodies, valve bodies, structural aerospace parts.
How it fits into a machining route
Horizontal 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: pallet utilisation, because an idle pallet is still a cost. 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 AS9100 or IATF 16949 depending on the customer. 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 with the part on its locating features 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 Horizontal 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?
316L stainless steel is the usual choice, supplied against AS9100 or IATF 16949 depending on the customer.
How is the result verified?
CMM with the part on its locating features, with the results recorded so a repeat order can be compared with the first.
What is the most common mistake?
The rotary axis not checked for backlash before a batch starts.
How long does it take and what does it cost?
A realistic cycle is 20 to 60 minutes per pallet, and the cost driver is pallet utilisation, because an idle pallet is still a cost.
Related capability
If you are specifying Horizontal 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 Horizontal Machining Centre in the encyclopedia: Turn-Mill Centre, Wire EDM Machine, Deep Hole Drilling. Reading them together gives a fuller picture of how the process, the material and the measurement affect each other.
