Skiving Machine

This machine is very important machine and is extensively used in leather goods manufacturing. It helps to reduce thickness of the leather components at the edges for easy folding. Only skilled persons can operate this machine as the quality of skiving depends on various adjustments and operation techniques. Different types of skiving viz. parallel skiving, channel skiving, taper skiving and fine edge skiving can be achieved
using appropriate presser foot. The skiving can be done to a width of 3mm to 50 mm

The skiving machines are built with a minimum number of moving parts which are amenable for vary fine adjustments and the operation of the machine made simple. Adjustment of moving parts is constantly required to affect different types of skiving and on different types of leathers that vary in thickness and softness. It is used …

  • For uniformity in quality.
  • For saving in time.
  • For mass production.
  • For what can’t be done by hand.

Various Parts of Skiving Machine:

1.  Sharpening Stone / grinding wheel:

Sharpening stone
Fig 1: Sharpening stone

A small fast rotating grinding stone. This is used to sharpen the knife, and should always spin away from the knife edge. The sharpening stone is driven by an endless woven flat belt.

2.  Bottom feed roller tension hook:

Bottom feed roller tension hook
Fig: Bottom feed roller tension hook

The tension is caused by a spring on the  other end of the hook. To adjust the tension, move the hook from one slot to the next. Tension is required to hold the feed roller close to the knife. 

3.  Guide:

Guide
Fig 3: Guide

 It determines the width of the skiving.

  • Guide position forward for decreased width of skiving.
  • Guide position backward for increased width of skiving.

4.  Pressure foot:

Pressure Foot
Fig 4: Pressure Foot

Determines the thickness to be skived for a given type of skive.  These are inter-changeable by a simple device for skiving narrow edge, deep curvature (grooving) and for skiving patent leather. Normally the  width of the skive is the same as width of the pressure foot. The width of skive is determined by the position of the guide. The thickness of the cut is regulated by adjusting the screw at the top of the pressure foot holder.

5.  Pressure foot adjusting screw and locking nut:

Pressure foot adjusting screw and locking nut
Fig 5: Pressure foot adjusting screw and locking nut
  • To adjust the pressure foot undo the locking nut by turning anti-clockwise.
  • Turn the adjusting screw clockwise to obtain a wider, thinner skive.
  • Turn the adjusting screw anti-clockwise to obtain a narrower, thicker skive.
  • Retighten the locking nut by turning clockwise.
  • When adjusting the pressure foot it is not to come in contact with the knife or feed roller.

6.  Pressure foot height adjusting screw:

Pressure foot height adjusting screw
Fig 6: Pressure foot height adjusting screw
  • Turn the height adjusting screw anti-clockwise to obtain a thicker edge.
  • Turn the height adjusting screw clockwise to obtain a thinner edge.

7.  Arm

Skiving Machine Arm
Fig 7: Skiving Machine Arm

8.  Material release lever:

Material Release lever
Fig 8: Material Release lever
  • If materials should become jammed in the machine, lift up the material release lever.
  • You can then withdraw the material from the machine.
  • Return the lever to its original position.

9.  Bed:

Skiving Machine Bed
Fig 9: Skiving Machine Bed

This is a resting place for completed work.

10. Belt cover: 

Belt cover
Fig 10: Belt cover
  • Safety covers to protect the operator from the machine’s pulleys and belts.

11.  Feed belts:

Feed Belt
Fig 11: Feed Belt

To change the machine feeding speed in relation to the knife speed. This can be adjusted by changing the pulley ratio of the feed roller drive belt.

12. Knife drive belt:

sharpening stone drive belt
Fig 12: Knife drive belt

13.  Sharpening stone drive belt:

Fig 13: sharpening stone drive belt

14. Hand wheel:

 Hand wheel
Fig 14: Hand wheel

15. Knife: Cylinder knife/Bell knife: A fast rotating circular knife of which the cutting edge is ground to a hollow level on the outer surface. The bell knife is made of a special chromium alloy of 12.0 cm diameter and 5.2 cm width.

Cylinder knife-Bell knife
Fig 15: Cylinder knife-Bell knife

16. Knife adjusting lever:

Fig 16: Knife adjusting lever

17.  Sharpening stone adjusting thumb nut

Sharpening stone adjusting thumb nut
Dig 17: Sharpening stone adjusting thumb nut

18.  Feed Roller:

Feed roller
Fig 17: Feed roller

A slow rotating roller made of abrasive material, which conveys the leather to the knife edge. The feed roller should never touch the bell knife or the pressure foot. 

19.  Feed roller adjusting screw

Feed roller adjusting screw
Fig 19 : Feed roller adjusting screw

20.  Treadle

Treadle
Fig 20: Treadle

21. Motor

Motor
Fig 21: Motor

22. Waste slide tray

Waste slide tray
Fig 22: Waste slide tray

23. Metal waste bin

Metal waste bin
Fig 23: Metal waste bin

Tools:

1.  Dressing tools: This tool is used to clean and reshape the edge of the sharpening stone.

2.  Adjustable spanner: To unlock and lock the feed roller adjusting screw locking out.

3.  Scissors: For undoing work bundles and leather cutting.

4.  Ruler: For accurate measurement of scarves.

5.  Thickness gauge: 

  • Check the calibration of the gauge, by closing it nothing between, the dial should register 0.
  • Place the material to be measured flat on the base.
  • Push down the anvil firmly and read the measurement of the gauge.

6.  Time clock: the clock is used for exercise timing.

Operation of Leather Skiving Machine:

  • Turn on the machine.
  • Make sure the sharpening stone is not touching the knife.
  • Check that the pressure foot is not touching the feed roller.
  • Check that the knife is not touching the feed roller.
  • Position the guide.
  • Depress the treadle.
  • Stack your work on the benchtop to the left of the machine.
  • Feed-in the leather with the grain side up.
  • Keep the leather to the guide.
  • Run straight through.
  • Place the skived place of leather upside down on the machine bed.
  • Pick up the next piece and skive as before.
  • When you have completed all pieces remove the pressure from the treadle to stop the machine.
  • Inspect, stack and tie up your work.

Safety requirement:

  • Switch off the machine when not in use.
  • To remove jammed material use a stick or brush.
  • Please scraps in a metal dust bin at the end of the day for a fire hazard.
  • Keep your work area tidy.
  • To protect the operator from the spinning belts use belt guard.
  • You should sit squarely on your chair within reach.
  • Know your fire drill
  • Do not try to make your own electrical repairs.
  • Don’t use loose dresses.
  • Keep your personal safety
  • Your movement easily in working place.
  • When you working in the machine not to be careless

Reference:

  1. MANUAL FOR LEATHER ACCESSORIES AND LEATHER GOODS ..SUBRAMANIAN NATESAN
  2. CFTC class note
  3. National Technical and Vocational Qualification Framework .. Notes



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