Application · Machining centres
On a vertical machining centre the hydraulics rarely move the tool — they hold the work. A VMC power pack’s job is to clamp fixtures and workholding firmly and repeatably, then hold that pressure rock-steady while the spindle cuts. That calls for a compact, reliable, continuous-duty unit that delivers a steady clamp pressure with no drift, sits close to the machine, and keeps the oil clean. This page sets out what VMC clamping asks of a hydraulic power pack, the typical requirements, and the right Suyog unit for the job.
A VMC uses hydraulic pressure to actuate workholding — hydraulic vices, fixture clamps, expanding mandrels and, on some machines, an indexing table clamp or a fourth-axis chuck. In each case the pack has to build a defined clamping force, then hold it without loss while the part is machined. The motion itself is short: the clamp closes in a second or two at the start of the cycle. The demanding part is the holding — clamp force must not drift while the tool is in the cut, because a part that shifts even slightly scraps the feature and can be dangerous.
Because clamping is brief and holding is passive, the flow demand is modest and the pump does not run continuously under load; a load-holding circuit maintains pressure while the pump idles or unloads. That keeps the unit small and cool. The premium is on steady holding pressure, compactness, and reliability shift after shift rather than on high flow or high power.
The figures below are typical, illustrative ranges for VMC fixture and workholding clamping — a starting point, not a specification. Your actual pressure follows from the clamping force each station needs and the clamp or cylinder bore that produces it (see the selection method).
| Parameter | Typical / illustrative range | Why |
|---|---|---|
| Working pressure | 40–160 bar (typical) | Set by clamp force ÷ bore; many hydraulic vices & fixtures run ~100–150 bar. |
| Flow | Modest — a few L/min (typical) | Clamping strokes are short; flow only sets how fast clamps close. |
| Reservoir | Compact tank (typical) | Low flow and intermittent duty keep the tank — and the footprint — small. |
| Control | Solenoid (DCV) per clamp circuit | Clamp/unclamp from the machine PLC; closed-centre spool to hold under load. |
| Relief / safety | Working pressure + ~15–20% | Protects fixture, clamps and pack; caps peak pressure. |
| Duty | Continuous-rated, intermittent load | Runs all shift; pump loads only to clamp, then holds. |
Ranges are typical and illustrative only. Final values come from your clamping force, bore, number of stations and duty cycle.
These Suyog units suit VMC fixture and workholding clamping. General sizing guidance is separate — the guides below cover the engineering; these are the products we build for the job.
Compact clamping unit designed around steady holding pressure for VMC fixtures and vices.
View product →Clamping and actuation power units for machining centres and machine tools.
View product →Proven standard HPUs where a catalogue unit fits the clamping duty.
View product →Built to your fixture, pressure, control and space envelope when the standard range doesn’t fit.
View product →These are general engineering references — use them to work out your own numbers before matching them to a Suyog unit.
The full step-by-step method from application to specified unit.
Read guide →Why pressure sets clamp force and flow sets clamp speed — independently.
Read guide →Turning working pressure and flow into the right motor kW.
Read guide →Run pressure, flow and motor-power numbers for your clamping duty.
Open calculators →Most VMC fixture and workholding clamping sits in a roughly 40 to 160 bar working range, with many hydraulic vices and fixture clamps specified around 100 to 150 bar (typical, illustrative figures). The exact pressure comes from the clamping force you need and the cylinder or clamp bore that produces it — pressure equals force divided by piston area. Set the working pressure at the required figure plus about 20% margin, then round up to a standard rating your pump, valves and gauge all share.
Yes. Tell us the clamping force per station, the number of clamps and whether they act together or in sequence, the working pressure your fixture or hydraulic vice is rated for, and the control you need. We size the pump, motor, reservoir and manifold around those figures and can match the port sizes, voltage and mounting to your machine so the unit drops in beside it.
The pump does not need to run the whole shift. Clamping is intermittent — the pack builds pressure to clamp, then a load-holding circuit maintains it while the pump idles or unloads. What matters is that the unit holds clamp pressure with no drift across the machining cycle and can rebuild quickly on the next part. Sizing the reservoir and, where duty is heavy, adding cooling keeps oil temperature and clamp force stable through a full production day.
VMC clamping needs modest flow, so the reservoir and motor stay small and the unit can sit on or beside the machine within a compact footprint. A small tank keeps the package tight; where the duty cycle is heavy we add a cooler rather than starving the reservoir. Vertical or submersible-pump arrangements save floor space further. Give us the space envelope and we will fit the unit to it.
Running a CNC lathe or turning centre instead? See Hydraulic Power Packs for CNC Machines, which adds chuck and tailstock actuation to the clamping picture.
Tell us about your VMC
Use the configurator for a full recommended configuration, or send your requirement and our engineers will match a unit to your fixture and machine.
