In leather industry Glazing machine is used to add shining on the leather. This machine consists of a reciprocating arm made of wood or steel. A glass rod is fixed to the free end of this arm. This glass rod reciprocates over a feed table on which leather is feed for polishing. To get good results Linseed oil is sprayed over the leather before it is feed to the glazing machine. The glass rod rubs against the leather surface which in turn polishes the leather and provides the desired shine.
The specifications of this machine are:
- Dimensions: Length 8’1” Height 7’10” Width 1’8”
- Glass rod dimension is Diameter 2” Length 4.7”
- Motor fixed with machine is of 3 phase 3 HP 2.2 Kw with RPM 900
- Machine arm reciprocates at 180 stroke/minute
The glazing/polishing process involves a lot of manual steps. The leather is feed manually in the machine from the front side. The operator has to hold the leather and adjust the polishing surface by standing beside the machine. This is the cause of major concern as may lead to accidents if the operator is not skilled and/or loses his concentration during the operation.
We are looking for solutions to make this operation safer in terms of guarding of the moving part of the machine. Specifically we are looking for solutions that will enable us to solve the following problems:
- During the operation of the machine if the wooden arm breaks then the machine must stop immediately and the broken piece should get arrested (in an enclosure).
- While feeding leather in normal course of operation the machine must stop immediately if the operator puts his hand /finger on the table below the machine arm / jaw and avoid getting injured.
- An enclosure that will act as protecting cover (as mentioned above) and will also allow the operator to see through it to monitor the operation occurring on the table.
We have tried the following solutions so far without getting satisfactory results:
- Reciprocating arm covered with perforated guard. Operator was finding it difficult to operate machine.
- Wooden arm replaced with steel arm. But it was giving more vibrations so discontinued.
- Main phosphor bronze bushes replaced with ball bearings. This has prevented failure of wooden arm but operator’s safety is still a problem
- Automatic greasing system was installed for regular lubrication of bush bearings
- One limit is switch installed that is connected to foot pedal. Pressing the foot pedal in case of any emergency will stop the main motor. This is not a full proof solution.
Figure 1: Machine operated by a skilled operator