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Flat Honing and Lapping with Two-Wheel Machines

By: A.W. Stahli / B. Stahli
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Work Pieces and Removal

In terms of the type of workpieces, the two-wheel machining process is more limited than single-wheel lapping machines, particularly in relation to the height of the contact surface,

Virtually all materials can be machined. However, the workpieces should have a certain thickness, as the machining forces are applied twice, depending on the rotation or counter-rotation of the working wheels.

  • Figure 18: Machining example “reinforced steel plate”
  • Figure 20: Machining example “plastic pump lid”
  • Figure 19: Machining example toothed-gear pump set made of sintered metal
  • Figure 21: Machining example
    “hydraulic volume regulator, cylind. lapped”
  • Figure 22: Machining example “clock circuit board, brass”
  • Figure 23: Machining example “bar, steel”
  • figure 24: Machining example “hard-metal circular knife”

Necessary data for machining

  • Drawing of the work pieces
  • Material and hardness
  • Pre-machining and allowance
  • Outer dimension, out shape, interrupts, unevenness, removal on one side, two sides, equal
  • Surface quality, flatness, parallelism, dimension and tolerances, grain selection, angularity, CPK values
  • Definition of : working process, working wheels, carriers, speeds, level loads, loading and unloading systems, etc.

In order to compensate for differences and irregularities, the system starts up with a pre-load. This is then followed by the main load, which is held shortly before the correct dimension. It can be calculated according to the definition of the working wheels, the work-piece surface, and the permissible, specific pressure load per N/cm squared. The post is used to equalize (like sparking out in grinding).

Notes for machining:

  1. The user must be able to determine how the removal is proceeding via the information display. If the machine is working to dryly, with too great a load or with dirt, the power consumption will increase. An increase in machining time also indicates a fault. A constant level should be achieved during the machining time.
  2. The speed and the liquid volume should be selected do that the lubricant film is always clean and fluid and optimal stock removal is guaranteed. Any jerky running under load indicates irregularities.
  3. Considering the machining time, the dimension constancy, the roughness, the flatness, and the parallelism can help you to draw conclusions about the status of the operating working wheels. Any negative changes must be countered in a good time.
Figure 25: Work pieces processed with loose and fixed grains

18-1: Diecast aluminum connecting rod, 0 30 * 100 * 12 mm, blank with over 1 mm allowance, cutting in 1 minute per load of 60 items, DLM 700, diamond D76, loading/unloading time with pulse system 1 minute (flathoning)

18-2: Intermediate plate in steel,0 40 * 15 * 3 mm, allowance 0.1 mm/side, punched, machining time 15 minutes per load of 100 items, DLM 700,cast-iron wheels, SiC 500, lapping oil (lapping)

18-3: Cutting wheel, 0 35/12 * 6 mm, made of steel, allowance 0.2-0.3 mm, punched pressed, machining time 2 minutes per load of 180 items, DLM 1000, D 126, honing oil (flathoning)

18-4: Ceramic disc made of Al2O3 0 35/15 * 5, allowance 0.4 mm, raw sintered part, machine time 1 minute per load of 65 items, DLM 700, D 76, honing oil (flathoning)

18-5: Indexable insert, approx. 25 * 13 * 6 mm, made of hard metal, unilateral allowance 0.1, opposite side 0.05, machining times 3 minutes per load or 200 items, DLM 700 with D$^, honing oil (flathoning)

18-6: Intermediate plate, O 20 * 6.5 mm, allowance 0.1-0.15, lathed, machining time 1.5 minutes per load of 200 items, DLM 700, D46, honing oil (flathoning).

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