Machine maintenance

Machines or equipment that is not maintained (or looked after) will not last long. A machine or equipment that must be replaced often adds unnecessary expense to the business, contributes to end of life waste, and drives consumption demand. Energy efficiency and sources of contamination are what hurt the tannery even more, however – it does not take long for a tannery to realise that it is in their interest to do maintenance. It does however require some thought, as keeping a parts inventory (with re-order trigger levels), scheduling of maintenance, and correct resourcing (personnel and consumables) are required.

Finishing machines, especially spray machines, get a slow build-up of finishing chemicals. The machines have the working face (spray rotors/guns, rollers, conveyors) that often encounter the finish and results in a significant build-up. The operator must also think about the working parts of the machine that may need replacement, or engineering level adjustment.

The typical types of maintenance that a machine would require are:

 

 

It is vital to maintain energy efficiency that the machines are kept clean and to ensure that the work does not get contaminated by dirt particles. It is not uncommon that light coloured leathers could be blighted by dark dirt contaminants (or dark leathers blighted by light dust or dirt).

The vibration of the machine will often dislodge particles that will then fall onto the leathers that are passing by. If the leather has a wet surface coating or brushes past a dirty spot, then the unsightly marks can be transferred to the leather and will often remain as a source of considerable downgrading of price.

 

 

Cleaning takes time, uses resources that add expense to the business operating costs, and can cause workers demotivation when the cleaning task is laborious or difficult. The removal of dirt of spraying equipment, or roller coaters, can be an example of difficult-to-clean equipment. The scraping and brushing to remove adhered finish off finish equipment is a frequent excuse of why tanneries do not like doing housekeeping. 

Figure 1 shows a common strategy used by tanneries to try to make the cleaning job a little easier. In the diagram on the left, a spray gun has a netting material stretched over the gun (especially the control devices) to ensure that when the gun needs cleaning then a sacrificial layer is simply removed and disposed of. The touch-up cleaning is then relatively quick and easy. The right-hand image of Figure 1 shows a fully exposed spray gun that will rapidly collect contamination, together with vibration the assembly will progressively give headaches as the control devices become difficult to adjust and the cleaning will be difficult and will frequently give rise to contamination.

 

 

The string conveyors (typically made of Perlon – a nylon material) that are commonly seen on the spray machines are sources of finish build-up. The strings contaminate the leather or build-up to the point that they snap because the string is fatter and undergoes tension when going around the machine drive assembly. The scraper and brush wash system that accompany the modern spray machine must be maintained to ensure that they are working effectively.

 

The wiring on electrical control panels that are associated with the machines are a vital part of the machine/equipment. Frayed wiring or exposed electrical connections can cause electric shocks to workers, can earth themselves (causing power outage) or in some cases can start serious fires. In tanneries that still use flammable solvents, the precaution with electrical connections is even more important. A naked spark can ignite solvents easily causing explosion or fire.

Exposed circuitry can also flash when liquids land on bared connections. Many of the machines use three-phase electricity which can severely injure workers if not isolated or insulated correctly.

 

A common area of cleanliness that is overlooked is the general decluttering around machines (or even inside machines). Residues, abandoned boxes, stored materials are often placed around machines through laziness, lack of storage space, or for convenience. The general rule for work in progress is that materials and ingredients should not appear in the production area unless they are imminently about to start process. Intermediate holding stages or finished materials should be moved out of the production area, so they do not clutter.

A cluttered area makes it exceedingly difficult to clean, slows traffic (and causes accidents), and can also be a great source of contamination. Open space around a machine makes it easier to adjust, problem solve and of course reduces the risk of fire.

 

An important part of finishing machine maintenance is the frequent addition of lubricants to working parts of the machines. The frequency, type, and lubrication point are governed by the instructions by the equipment manufacturer. The most common reason that lubrication is not performed is that the lubricant required is exotic, the access to lubrication points is hindered, or that the finishing manager is not working with the engineering maintenance team (or sub-contractors) to ensure that the logistics and schedule of maintenance is not correctly structured. It could also be the case that the area that needs lubrication is faulty and the lubricant simply runs out of the assembly and poor lubrications is not performed.

Under-lubricated machinery wears more rapidly, overheats (with possible seizures), or at the very least will experience frictional movement, which is a force in opposition to the normal function of the machine. Frictional movement drastically reduces energy efficiency and wastes energy that did not need to be used. Waste costs a tannery.