PG40 120×120 mm Twelve Slot Aluminium Strut Profile with 62 mm Centre Bore

What a 62 mm through bore is actually for

Routing a cable or hose bundle down the structure

A 62 mm bore will take a substantial harness — several power cables, signal cables and a pneumatic line, with room to spare and without them being clamped against anything sharp. On a large machine, a gantry or a robot cell, running the services inside the column rather than along the outside is the difference between a machine that looks finished and one that looks like a prototype. It also protects the cable from swarf, coolant and impact, and it removes the snagging risk on a moving axis.

The bore is also a natural place for the cable to change direction, because you can break out of it at any point along the column by drilling through to the surface between two slots.

Passing a shaft, screw or spindle through the column

A 62 mm bore will pass a 50 mm shaft with clearance, or a 40 mm ball screw complete with its support bearing. That makes the column usable as a structural sleeve rather than only as a frame member: an axis can travel inside the structure, which is how a compact lift, a rotary indexer or a telescopic mast is built without an external guide.

It is worth being clear about the tolerance here. The bore is an extrusion feature, so it is straight but not a bearing fit. Where the shaft needs to be located accurately, bore the ends and fit a bearing housing rather than running the shaft directly on the extrusion.

Removing weight and material from the section

A solid 120 x 120 mm aluminium bar weighs about 39 kg/m. This section weighs about 9.4 kg/m, so roughly three quarters of the material in the envelope has been taken out — and the 62 mm bore is the largest single removal. Because the material sits near the outside where it carries bending stress, taking it out of the middle costs far less stiffness than the weight saving suggests. That is the same reason a tube is more efficient than a solid bar, taken to its logical conclusion inside a T-slot profile.

Twelve slots and the multi-directional node

Twelve slots on a 120 x 120 mm section means three mounting positions on each face, and that changes how a large frame is built. At a corner, members can arrive from four directions without any of them competing for a slot, and a cross member can be bolted through the middle of a face rather than at its edge. On a big structure that is what keeps the node count down.

The eight Ø12 mm bores tapped M14 are the structural fixings. They sit on an 80 mm square pattern, which is the same 80 mm as the outer slot spacing, so a bracket or an end plate can be designed once and used on either. Use the bores for anything carrying load and keep the slots for what has to be adjustable.

Why large sections are made to order

Below about 100 mm square, T-slot sections are standard products that distributors hold in stock. Above that, the economics change. A 120 x 120 mm die is a large piece of tooling, the extrusion press has to be big enough to push it, and the run length needed to make the setup worthwhile is measured in tonnes rather than metres. The result is that sections this size are normally extruded against an order rather than held on a shelf.

For you that has two practical consequences. Lead time is longer than for a small section, and the minimum order quantity is higher. In exchange, a section this size is a candidate for a custom die: if the standard 120 x 120 is close but not right, the tooling cost is spread over a long enough run to be worth considering. Tell us the envelope you actually need and we will say whether a custom die makes sense.

Frequently asked questions