Honing Machines have the capability to hone surfaces at different angular orientations using rocking motion to produce the stroking when honing in one orientation and linear motion to produce the stroking when honing in a different angular orientation that allows for extreme control while delivering a consistent crosshatch pattern throughout the entire length of the hole.
Typical small bore applications for Honing Machines include hydraulic valves, cartridge valve bodies, fuel injectors, gears, including transmission and other precision gears, gun barrels, including pistol and machine gun, gear hobs, refrigeration compressor components, turbocharger housings and bearings and connecting rods. Typical large bore applications include 2 cycle engines, diesel liners, all types of engine blocks, gear hobs, landing gear components, large connecting rods and bearing sleeves.
Honing is a low-velocity abrading process. Material removal is accomplished at lower cutting speeds than in grinding. Therefore, heat and pressures are minimized, resulting in excellent size and geometry control. The most common application of honing is on internal cylindrical surfaces.
Machining a hole to within less than 0.001" in diameter and maintaining true roundness and straightness with finishes less than 20[micro]" is one of the more difficult jobs in manufacturing.
Honing can consistently produce finishes as fine as 4[micro]" and even finer finishes are possible. It can remove as little as 0.0001" of stock or as much as 0.125" of stock. However, usually only 0.002" to 0.020" stock is left on the diameter for honing.¹
For most work, honing machines are quite simple. The most-used honing machines are made for machining internal diameters from 0.060" to 6". However, large honing machines are made for diameters up to 48". Larger machines are sometimes made for special jobs.
The length of the hole that can be honed may be anything from 1/2" to 6" or 8" on smaller machines and up to 24" on larger machines. Special honing machines will handle hole lengths up to 144".¹
Vertical Spindle Machines
Vertical-spindle honing machines are used especially for larger, heavier work. These all have power stroking at speeds from 20 to 120 Thin. The length of the stroke is also machine controlled by stops set up by the operator.
Vertical honing machines are also made with multiple spindles so that several holes may be machined at once, as in automobile cylinders.¹ Some machines include bi-directional rotary tables with flexible variable servo positioning.
Hone body: The hone body is made in several styles using a single stone for small holes, and two to eight stones as sizes get larger. The stones come in a wide variety of sizes and shapes. Frequently, there are hardened metal guides between the stones to help start the hone cutting in a straight line.
Cutting fluid: A fluid must be used with honing. This has several purposes: to clean the small chips from the stones and the workpiece, to cool the work and the hone and to lubricate the cutting action.
A fine mesh filtering system must be used, since re-circulated metal can spoil the finish.¹
Honing will not only remove stock rapidly, but it can also bring the bore to finish diameter within tight tolerances. This is especially true if the honing machine is equipped with automatic size control. With every stroke, the workpiece is pushed against a sensing tip that has been adjusted to the finish diameter of the bore. When the bore is to size, the sensing tip enters the bore and the machine stops honing. Size repetition from bore to bore is 0.0001" to 0.0002". The operator simply loads and unloads the fixture and presses a button; everything else is automatic.
Single Pass Honing: A still faster and more accurate method of honing a bore to final size is single-stroke honing. The single-stroke tool is an expandable diamond-plated sleeve on a tapered arbor or a fixed-sized tool coated with diamond abrasive particles. The sleeve is expanded only during setup. No adjustments are necessary during honing. Unlike conventional honing, where the workpiece is stroked back and forth over the tool, in single-stroke honing the rotating tool is pushed through the bore one time, bringing the bore to size. The return stroke does nothing to the bore except get the workpiece off the tool. Single-stroke honing is so accurate and consistent that honed bores do not require gaging.¹
Liberty Machinery buys and sells Honing Machines.
Used Honing in Stock: Accu-cut, Engis, Sunnen
1. Schneider, George Jr., CMfgE, Cutting Tool Applications, (2002) pp. 217-221