Machining
guidelines for Vesconite.
Vesconite
is easily machined to fine tolerances on standard metal working
equipment.
| Turning | Tool
cutting angles Cutting speeds Machining standard bearings with diameters < 200 mm Bearing groove design Machining bearings with diameters > 200 mm |
| Drilling
solid rod Milling Sawing |
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Please refer to the Material Safety Data Sheet for Vesconite for material safety precautions.
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 - 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) | |
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.
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| 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.
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| Step 5 – Part to
length Part bush to length using parting tool. Ensure that bush does not fall when parted.
|
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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.
-
Face the end furthest from the chuck
-
Machine the inside diameter
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Machine the outside diameter
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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
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
-
Secure the bearing in the chuck or pot and lock the chuck.
-
Attach a broaching tool to the tool post.
-
Set up the tool and machine a groove taking no more than 2 mm with a cut.
-
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
-
Use high speed twist drills
-
Drill a pilot hole of ±15mm initially
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Cooling is very important. Use cutting fluid or water. This is one of the biggest reasons for failures.
-
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.
-
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°
Updated Nov 29 2002
