Not only hoses: what else a crimping machine can do
A radial press is a controlled source of circumferential force. By changing the dies and the control mode it assembles power-line insulators, seals battery cells, calibrates tubes and crimps wire rope.
The classic job of a crimping machine is a fitting on a high-pressure hose. But by its principle the machine performs one operation: it applies a large, uniform and precisely controlled radial force to a part. Everything else is decided by two settings — the die profile and the control mode. We covered profiles in detail in the article on dies; here we talk about modes and the tasks they open up.
Two modes: by diameter and by pressure
A CNC machine can stop the crimp in two ways:
- By diameter — the dies close to a set size. This is the standard for hoses: what matters is the final ferrule diameter, and the force is whatever it takes.
- By pressure (force limiter) — the machine crimps until the hydraulic pressure reaches a set threshold and stops, whatever the current diameter. The force on the part never exceeds the limit.
The pressure mode makes it possible to work with fragile parts, for which excess force means cracked ceramics, crushed fibres or a dented thin wall. It also compensates for workpiece scatter: parts with varying dimensions receive the same force rather than the same diameter.
Fragile parts: crimping with force limit
Composite power-line insulators
A polymer insulator is a fibreglass rod with metal end fittings crimped onto both ends; through them the insulator carries the entire mechanical load of the line. The crimping requirements here are contradictory. If under-crimped, the rod eventually slips out under conductor tension; if over-crimped and the glass fibres are crushed, the rod loses its strength. Industry statistics explicitly name poor crimping of end fittings among the causes of mechanical failure of insulators on lines. That is why end fittings are crimped with force control: the machine guarantees that the pressure on the rod stays within the design window.
Ceramics in sensors and plugs
Spark and glow plugs, oxygen sensors, high-voltage bushings — everywhere a metal shell is crimped around a ceramic insulator. Ceramics do not forgive point overloads, so crimping is done with a uniform ring and strictly by force, often with a stepped pressure rise.
Sealing of battery cells
The cap of a cylindrical cell is held by the rolled edge of the can through a polymer gasket. The force here is directly linked to tightness: if the gasket is under-compressed it leaks electrolyte, if over-compressed it cracks over time. Pressure-controlled radial crimping gives stable sealing across the whole batch despite can tolerances.
Thin-walled tubes
These are heat-exchanger tubes, temperature-sensor sleeves, filter housings. Crimping connecting elements onto a thin wall in pressure mode leaves no dents and does not distort the channel geometry.
Shape and size: crimping by diameter
The second group of tasks uses the classic diameter mode and special die profiles:
- Tube end calibration — removing ovality after cutting and bending before machining or welding.
- Reducing for telescopic assembly — a step on the tube end that enters the mating tube: roof snow guards, playground frames, railings — joints without welding.
- Bead stops and annular grooves on tubes — stops for hoses, springs, bearings.
- Wire rope and slings — crimping aluminium and copper ferrules: the joint holds in tension as well as the rope.
- Large cable lugs — uniform crimping without pinching the strands.
Die profiles for these tasks are described in detail in the article "Crimping dies: why the surface decides everything".