Slotting Machine Product

Overview

A slotting machine, or slotter, is a vertical shaper. A reciprocating Ram Assembly drives a single-point Slotting Tool straight down through the workpiece, shaving off a chip on each stroke, then the work advances a fraction of a millimetre and the next stroke repeats. The geometry that justifies the machine is internal: keyways inside bores, internal splines, square and hexagonal holes, dovetails in blind cavities — features a rotating cutter cannot generate because there is no room for the cutter body or no exit for it. A broach does the same work faster in production quantities, but a broach is a dedicated tool per profile; the slotter cuts any profile with a tool bit ground in minutes, which keeps it alive in job shops, repair work, and one-off die making.

Drive and ram

Power flows from the Main Motor through V-Drive Belt stages and the Speed Gearbox to the Bull Gear inside the Column Casting. The Crank Drive converts that rotation into reciprocation: a Crank Pin clamped in the radial slot of the Crank Disc drives the Connecting Rod, which rocks the ram. Stroke length is set by moving the pin radially with the Stroke Adjuster — pin at centre gives zero stroke, full radius gives 320 mm. The linkage geometry yields a quick return of about 1.4:1, so the idle upstroke wastes less of the cycle than the cutting downstroke takes.

The Ram Body runs on scraped vertical Ram Guideway surfaces; a Ram Counterweight inside the column balances its mass so the crank sees a roughly uniform torque, helped by the Flywheel which carries the drive through the shock of tool entry at each stroke. Cutting forces reach roughly 18 kN at the tool, all of it reacted as a vertical blow into the Bed Casting — slotters are deliberately massive for their working envelope.

The tool itself clamps in the Tool Head at the ram foot. Unlike a lathe tool it cuts on its end face, with side clearance ground to the slot width. On the return stroke the Tool Relief Mechanism mechanism backs the cutting edge slightly off the machined face; without it the flank rubs and work-hardens the cut surface, dulling the tool within minutes.

Table and feeds

The work sits on the Rotary Table, the feature that separates a slotter from a shaper turned on end. The T-slotted Table Top rotates on an annular Table Circular Way way, driven through a 90:1 Table Worm Drive with a Index Plate on the worm shaft. This turns the machine into a gear-cutting and spline-cutting tool: index the plate one division per tooth space, cut, repeat. Curved slots are cut by feeding the table rotation continuously under the stroking tool. During each cut the Table Clamp locks the table dead.

Beneath the table, the Saddle and Cross Slide give two straight-line feeds on the Bed Casting ways, with play taken up by tapered Gib Set strips. All three feeds — longitudinal, cross, and rotary — are driven intermittently by the Feed Mechanism: a Feed Cam on the bull gear shaft rocks a linkage once per revolution, timed to the upstroke, and the Pawl and Ratchet converts the rock into a settable increment of 0.05-0.5 mm routed to the chosen axis by the Feed Selector. The work therefore never moves while the tool is in the cut. Positions are read from Feed Dial collars graduated to 0.02 mm.

Operation

A typical internal keyway job: the bored workpiece is centred on the table over the central bore so the tool can pass through, clamped, and the stroke positioned with the Drive Clutch inching the ram so the tool clears the bore top and bottom. The operator selects a stroke rate from the Gear Shift Lever — slow for long strokes in steel, faster for short strokes in cast iron, keeping cutting speed in the 10-25 m/min range of HSS tooling. Cross feed is engaged at perhaps 0.2 mm per stroke and the keyway deepens automatically to the dial reading. For a 4-spline bore the same cut is repeated four times with the index plate advanced a quarter turn between cuts.

Lubrication is a one-shot Lubrication Pump serving the ways and crank Crank Bushing bearings; electrics are minimal — a star-delta Motor Starter, Relay safety chain, and the Push-Button Station. The design has barely changed since the 1900s because nothing about the job has: it remains the cheapest way to put an accurate keyway in one gear blank.