USEFUL RULES FOR A CORRECT HONING

If you want obtain a good honing, it is necessary to follow some easy rules:

1. Selection of the honing unit. The appropriate honing unit to work must be selected relatively to the phisical bore characteristics, the type of material, and the requested tolerances;
2. Selection of the stones. The correct selection of stone permits you to obtain the wanted results, avoiding waste of abrasive, time, energy and money;
3. Rotation spindle speed. This speed have to be selected relatively to the diameter you have to hone: generally, the speed must be low for large bores, high for small bores;
4. Bore preparation. If you better prepare a bore, you will obtain a better, quicker and cheaper honing; so, it suggested to prepare the bore with accurate operation of drilling and boring;
5. Bore Deburring. When a bore has been worked without care with tools, or in quick way, it will have very marked imperfection; if a bore has burrs or very rough surface, it is firstly necessary to carry out a quick operation of deburring with very hard stones (deburring stones), so that damages to the removing stone and finish stone are avoided. This operation will reduce the stone wear and economy the production;
6. Working Tolerances in pre-honing operation. Generally, it is suggested to leave a sufficient quantity of work allowance in order to avoid any defect in the bore with the honing operation. For example: to hone a hole made with a twist drill, you need about mm 0,2 (0,008") of working allowance; instead, for a reamed bore, you need about mm 0,05 (0,002"). For the honing operation you only need a few hundred of mm, while for the lapping operation, you need to use very fine finishing stones, bronze guide shoes, and working allowance that must be no more than 1/100 of mm;
7. Honer preparation. It is necessary choose the right honer and prepare it in order to obtain a good honing; so, it is essential to leave stone and guide shoes parallel to each other: for this scope, CAR Srl supplies a sleeve specific for each honer (only on request) which is called truing sleeve;
8. Honer Stroke. Generally, during the honing operation, the stone must protrude about 1/3 or 1/4 of its length, in both extreme ends of the hole. For example: if you are using a stone which has a length of 100mm, in both the ends, it will have to protrude of 30mm. The stroke speed on the piece must be in ratio with the spindle speed, so that the honing crossing is from 30° to 90° inclusive; if it is possible, you have to keep a low honing pressure on the stone: this guarantees a long life of the abrasive. Set up the piece many times during the honing operation;
9. Termic treatments. When a piece has been worked with termic treatments, it presents some deformations; with the honing operation, leaving a right working allowance, you will correct deformations like bellmut, barrel shape, rainbow, taper, waviness and ovality,… without modify the primitive axe;
   
   
10. working of Blind holes. A bore is called "blind hole" when it has a smaller diameter in one of two extremes, or when it is close. When you prepare the piece, if possible, make an undercut in the blind hole: this permits the stone to work better because it has the possibility to have a correct stroke. However, please contact us for more specific details about this particular working;
    
11. Bores with Keyways or interruptions. To work these kind of holes, it is necessary to select honers type "TL" or "TX" specificly studied by CAR Srl.

IMPORTANT: in all honing systems an operation, manual or automatic, with any kind of abrasive, it is indispensable to use the AT 20 CAR Srl Honing Oil; it guarantees better removal and roughness results, lower abrasive consuption (until the 35% less), and loer working times (unitl 30% less). Moreover, it is suggested to keep the AT 20 Oil, constantly clean with normal filtering and decantation operations.

THE HONING