Machining Guidelines

Machining Guidelines for Vesconite

Vesconite and Vesconite Hilube are easily machined to fine tolerances on standard metal working equipment.

Vesconite should not be clamped like a metal, but should be clamped gently and with care to avoid distortion.

Cooling water should be used where possible to cool the cutting surface.

Take cuts no more than 2 mm (0.1") deep at a time.

Allow the bush to cool before taking the final cut.

Cutting Speeds and Feeds

Cutting speeds - Maximum of 300 m/min (1000 fpm)

Diameter (mm)	200	300	400	500	600	700
Diameter (inches)	8"	12"	16"	20"	24"	28"
RPM	350	300	200	150	100	70

Cutting Feeds

Rough turning	0,5 - 0,7 mm per revolution (0.020" - 0.030" per revolution)
Finish turning	0,3 - 0,4 mm per revolution (0.012" - 0.016" per revolution)

Tool Cutting Angles

Machining straight and flanged bushes for small quantities

(Machining standard bearings. Diameters < 200 mm (8"))

Step 1 – Cut to length

Allow extra length for chucking, parting and facing, usually 25 mm (1").

Cut bushing stock to required length using a cut-off saw.

Step 2 – Chuck with internal support disc

Set the bush in the chuck as squarely as possible.

Use an internal support disc machined to size. The disc can be made of any available material, approximately 10 to 25 mm thick (½" to 1").

Tighten the chuck lightly, but only enough to support the bush. Vesconite should not be clamped like a metal.

Step 3 – Machine inside diameter

Machine bush inside diameter using a boring bar. Ensure that there is not an excessive build-up of shavings inside the bush.

Grooves may be added at this stage if required.

Step 4 – Machine outside diameter

Machine bush outside diameter using an external turning tool.

If required, machine flange outside diameter.

Face the end of the bush to length.

Step 5 – Part to length

Part bush to length using parting tool.

Ensure that bush does not fall when parted.

Machining in NC lathes

Bushes can also be machined on numerically controlled lathes.
Take care to ensure that the clamping pressure does not distort the Vesconite.

1. Face the end furthest from the chuck
2. Machine the inside diameter
3. Machine the outside diameter
4. Cut to length at the chuck end

Machining standard bushes for production runs

When machining many Vesconite bushes on center lathes, the following procedure saves time and minimises waste.

Step 1 – Cut to length

Cut bush to final length using a cut-off circular saw. Take care to ensure that the cut is square.

If a fine length tolerance is required, allow extra material for facing both ends of the bush later.

Step 2 – Machine outside diameter

Machine two mandrels with outside diameters the size of the inside diameter of the Vesconite bushing.

Machine one for the chuck and another for the tail stock.

Mandrels can be made of Vesconite, steel or other readily available rigid material.

Support the bush between these two mandrels by applying a light pressure, and machine outside diameter using external turning tool.

Step 3 – Machining the inside diameter

Machine a "pot" with suitable available material (eg Vesconite, steel, etc). The inside diameter should be size to size to the outside diameter of the bush already machined.

Make the length of the pot about 10-25 mm (½" to 1") shorter than the length of the bush. The wall thickness of the pot must be sufficient to support the bush.

Drill a hole in the end of the pot so that the bush may be removed after machining by pushing a rod through this hole.

Machine a disc to be placed loosely inside the pot for removal of the part after machining.

Push the bush lightly into the pot.

Machine the bush inside diameter using a boring bar. Ensure that there is not a large buildup of shavings inside the bush being machined.

Grooves or other internal details may be added at this stage.

Machining bearings with grooves

Bearing groove design

Machining spiral and round grooves

This is done on the NC or manual lathe by normal operating procedures.

If the groove continues right through the bearing, it will usually be required to face the bearing after cutting the grooves.

Machining straight grooves

1. Secure the bearing in the chuck or pot and lock the chuck.
2. Attach a broaching tool to the tool post.
3. Set up the tool and machine a groove taking no more than 2 mm with a cut.
4. Index the chuck to the next point and repeat the process.

Machining large bearings. Diameters >200 mm (8")

Due to the size of these bearings, extra care needs to be taken to ensure that there are no unnecessary stresses placed on the material. These bearing are referred to as XL bearings.

Vesconite XL bearings are easily machined on standard lathes if proper support is provided to prevent deformation and cracking.

Remember that Vesconite should not be clamped like a metal, but should be clamped gently and with care to avoid distortion.

Allow 50 mm (2") extra length for holding and parting the bearing.

Step 1

Set the bearing in the chuck. First face one end of the bearing square. This helps with alignment.

To prevent deformation and cracking, it is important to use an internal support disc machined to size. This disc may be machined from steel, wood, particle board or plywood about 30mm (1¼") thick.

The jaw clamping pressure should not be excessive but only enough to secure the bearing.

Step 2

Switch bearing around, align and face the other end. Once again the internal support is required.

Step 3

Machine the outside diameter of the bearing. Maximum cut depth is 5 mm. Allow bearing to cool before taking final cut. Final cut to be no more than 2 mm deep.

Step 4

Machine the inside diameter without removing the bearing from the chuck, and with the support disc in place. Ensure that there is not a large buildup of shavings on the tool. Maximum cut depth is 5 mm. Allow bearing to cool before taking final cut. Final cut to be no more than 2 mm deep.

Step 5

Face the bearing to the required length taking care that the bearing does not fall.

Please refer to the Material Safety Data Sheet for Vesconite for material safety precautions.

Drilling solid rod

Drilling a large diameter Vesconite rod:

1. Use high speed twist drills.
2. Drill a pilot hole of ±15mm initially.
3. Cooling is very important. Use cutting fluid or water. This is one of the biggest reasons for failures.
4. It is very important to remove the shavings when drilling. It is best to regularly withdraw the drill and remove shavings, and then only continue with drilling.
5. Once the 15mm hole is achieved, machine to the required inside diameter using a boring bar on a lathe. Do NOT use a larger drill, this could lead to cracking.

Sawing

Use band saws and circular saws for Vesconite. If possible use saws with offset teeth to minimize heat build up and blocking of the saw.

Band saw

Tooth pitch 3-5 mm

Saw speed 200-500 m/min

Circular saw

Tooth pitch 8-12 mm

Saw speed 500-1500 m/min.

Milling

Use single point tungsten carbide tipped fly cutters or alternatively staggered tooth cutters.

Cutting Speed	500 m/min
Feed rate	0.1 - 0.5 mm/rev
Tool relief angle	5° to 10°
Tool rake angle	0° to 5°