Guide Components

Guide components do two separate jobs. Pillars and bushings hold the two mould halves in a known relationship while they close. Angle pins, fixing blocks and seats convert that closing motion into side-action movement. Parts that look similar in a catalogue behave very differently depending on which job they are doing.

Guide pillars and shoulder bushings

A guide bushing is a sacrificial part by design. Pair the hardness deliberately so the wear goes into the bushing, which is cheaper and quicker to replace, rather than into the pillar or the plate bore. Two parts at the same hardness sliding against each other gall instead of wearing evenly. Clearance has to allow for thermal growth — the fit you set on the bench at 20 °C closes up on a tool running at 100 °C, and a mould that runs sweetly cold and seizes hot usually has this problem rather than a lubrication problem. Where the mould cannot be greased, oil-groove or graphite-plugged bushings carry their own lubricant; the grooves must not break out of the bearing area at either end of the stroke.

Angle pins

Sideways travel equals the opening stroke multiplied by the tangent of the pin angle, so a 20° pin moves a slide by about 0.36 mm for each millimetre of opening. Most work sits between 15° and 25°. Steeper gives you more travel in less opening, but side force on the pin rises with it and the pin starts to bend, which shows up as a slide that binds only when the mould is hot. Check engagement through the whole stroke, not just at the ends: the pin must still be in the slide bore when the slide has to start moving, and clear of it before the mould is fully open.

Fixing blocks, seats and heel blocks

An angle pin fails at the head, not in the middle, because that is where the bending moment is highest. How deeply the seat supports the pin root, and whether the mouth of the seat is radiused rather than sharp, decides how long it lasts. The bore angle in the fixing block must match the pin angle — a block bored 18° with a 20° pin loads the pin on one edge. And the heel or locking block, not the pin, should hold the slide closed under injection pressure: make it 2–3° steeper than the pin so it takes the load once the mould is shut.

Interchangeability

Where a listing references a standard series, that is for identification only. Confirm the mating dimensions against your own mould before approving a quotation — flange diameters and shoulder lengths differ between systems that share a nominal size.

What to send with an enquiry

• Part number or reference series, or a drawing with revision
• Diameters, lengths, shoulder and flange dimensions, angle
• The mating bore, post or slide dimension where fit matters
• Material, hardness and surface treatment
• Quantity, destination and required date