Cylindrical Grinder Product

Overview

A cylindrical grinder produces the final, accurate surface on round parts — bearing journals, hydraulic rods, machine spindles, gauge pins. The workpiece rotates slowly between centers while a fast abrasive wheel, fed into it a few micrometres at a time, removes material left by turning or hardening. Where a lathe holds 10-20 µm, a cylindrical grinder routinely holds 2 µm on diameter with roundness under 0.5 µm and finishes of Ra 0.1-0.2 µm, on hardened steel that single-point tools cannot economically cut.

The machine's accuracy is built into iron and oil rather than electronics. The Bed Casting is a multi-tonne, naturally aged casting whose hand-scraped V-and-Flat Ways guides constrain the table to a straight line within 2-3 µm over a metre. Everything else — wheel, work, gauge — is referenced to those ways.

Wheel and wheelhead

The Wheelhead carries a 455 mm vitrified aluminium-oxide Grinding Wheel running at 45 m/s. The Wheel Spindle turns in Hydrodynamic Bearing pads rather than rolling elements: the spindle floats on a pressurized oil wedge that averages out surface errors and damps vibration, the property that lets the wheel leave a scratch-free surface. A flat Drive Belt from the Wheel Spindle Motor avoids transmitting motor pulsation, and a Pressure Sensor interlocks the spindle against running without lubrication.

Wheel balance is critical — 1 g·mm of unbalance at 1,900 rpm shows up as visible chatter marks. The wheel mounts between blotter-faced Wheel Flange pairs and is trimmed with the Wheel Balancer, a hub with movable weights, after each dressing. The Wheel Guard is rated to contain a wheel burst at maximum speed.

Grinding wheels do not stay sharp or round; they load with swarf and glaze. The Wheel Dresser restores them: a single-point Diamond Dresser held in the rigid Dresser Holder is traversed across the wheel face by the Dresser Slide at 0.01-0.03 mm depth, truing the face and fracturing fresh cutting edges into the grain. The control then offsets the infeed axis by the dressed amount so part size is unaffected.

Work drive and table

The Workhead rotates the part at 30-300 rpm — wheel and work surface speeds are typically in a ratio near 100:1, with the work turned against the wheel direction at contact. For the highest roundness the Workhead Spindle is locked: the part turns on two dead Work Center points, driven by a dog on the Drive Plate, so spindle bearing errors never reach the work. The Tailstock supports the far end through a spring-loaded Tailstock Quill, retracted for loading with the Quill Retract Lever.

The work setup rides the Table Assembly. The Lower Table traverses along the bed (the Z axis) to carry the part past the wheel; trip points are set with Table Trip Dog stops or programmed in CNC. On top, the Upper Swivel Table swivels a few degrees via the fine Swivel Adjusting Screw — this both grinds intentional tapers and corrects unintentional ones: if the part measures 2 µm larger at one end, a minute swivel of the upper table nulls it out.

Infeed and sizing

Diameter is governed by the Infeed Mechanism axis. The Infeed Slide advances the whole wheelhead on a fine-pitch Ball Screw with Encoder feedback at 0.1 µm resolution; the Infeed Handwheel reads 1 µm per division for manual work. A typical CNC cycle programmed in the Grinding Controller runs: rapid approach, rough infeed at 5-10 µm per table pass, fine infeed at 1-2 µm, then spark-out — several passes at zero infeed while elastic deflection in the system relaxes and the last fraction of a micrometre comes off. The In-Process Gauge Head rides the workpiece during the cycle and signals the control to retract the instant the target diameter is reached, removing wheel wear and thermal drift from the size equation.

Coolant

Grinding puts most of its energy into heat at a tiny contact arc, so the Coolant System delivers a heavy flow through the Coolant Shoe directly into the contact zone — a nozzle shaped so the jet matches wheel surface speed and penetrates the air barrier the wheel drags around itself. Cleanliness matters as much as volume: returned fluid passes a Magnetic Separator and a Paper Band Filter band, because recirculated grit above a few micrometres scratches the finish the machine exists to produce. Without adequate cooling the work skin overheats, leaving grinding burn — localized tempering and tensile residual stress that condemns hardened parts.