CPT

®

Thread Turning Technical Section

Example No. 3:

Step 1:

Choose Thread Turning Method from page A04-5 We chose EX-RH Insert & Toolholder.

EX-RH. AMERICAN BUTTRESS 12 TPI on 40 mm diameter.

Stainless Steel 304

Choose Insert from page A01-31: 16 ER 12 ABUT Choose Toolholder from page A02-3: SER 2525 M16 Choose Insert Grade from selection on page A04-2 Our choice for Stainless Steel is Grade BMA Choose Thread Turning Speed from chart on page A04-3 We chose 120 m/min. Rotational Speed calculation: Choose Number of Threading passes from table on page A04-5. We chose 13 passes Find Thread Helix Angle: on page A02-19 for Pitch of 12 TPI and 40 Diameter Helix Angle as shown in the chart is 1º Choose correct Anvil: As can be seen from the chart on page A04-7, for AMERICAN BUTTRESS Thread, for 12 TPI and 40 Diameter a negative anvil AE16-1.5 should replace the standard anvil supplied with the toolholder 120 1000 954 40 RPM

Step 2: Step 3: Step 4:

Step 5:

Replacing the standard anvil with an anvil with negative angle will eliminate side rubbing

Step 6:

Step 7:

Step 8:

Anvil chosen: AE16-1.5

Troubleshooting

Chipping

Crater Wear

Build-up Edge

1. Use a tougher carbide grade 2. Eliminate tool overhang 3. Check if insert is correctly clamped 4. Eliminate vibration

1. Reduce cutting speed 2. Apply coolant fluid 3. Use a harder carbide grade

1. Increase cutting speed 2. Use a tougher carbide grade

Thermal Cracking

Deformation

Fracture

1. Use a tougher carbide grade 2. Reduce depth of cut 3. Index insert sooner 4. Check machine and tool stability

1. Reduce cutting speed 2. Apply coolant fluid 3. Use a tougher carbide grade

1. Use a harder carbide grade 2. Reduce cutting speed 3. Reduce depth of cut 4. Apply coolant fluid

A04-9

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