Screw or piston air compressor? How to make the right choice?

Air compressors are equipment that we don't usually talk about, but they are as important as any other machine in the production flow. In addition to their use in various applications, they are necessary to operate different groups of machines, such as the precise end cutting group in edgebanding machines, for example. 

When it comes to compressors, we have 2 models: screw compressors and piston compressors. The choice between these 2 models depends on several factors: the available budget, performance requirements, the amount of air you use day to day, and the type of application it will be integrated into (industrial or intermittent use).

What is an air compressor and how does it work?

An air compressor is a mechanical device that compresses (reduces the volume of) atmospheric air and stores it under pressure in a tank (cylinder). The compressed air can then be used in various production, commercial, or domestic applications. 

Through compression, air becomes denser and can be used for a variety of purposes, from powering pneumatic tools to industrial processes, painting or ventilation.

What are the main applications of an air compressor?

Air compressors are used in a wide variety of industries, but we will focus on the woodworking industry. 

The main applications where an air compressor is needed are:

• Air supply of the various tools or groups that are part of a particular machine. Edgebanding machines, CNC routers, circulars to be formatted in a package or automatic painting machines are just a few examples that require compressed air in reasonable quantities to operate. Also, some hand tools require compressed air to perform the applications for which they were designed.
• dyeing. Here the need for such equipment is obvious. Constant, adjustable and consistent pressure ensures a uniform finish. Along with the capabilities of the painter, the use of a high-performance air compressor can deliver very good results.
• Equipment maintenance. Compressed air can help remove certain residues present in hard-to-reach places, thus increasing the lifespan of the equipment. DANIBRUM technicians recommend cleaning all equipment with compressed air after each working day, to eliminate the risk of accidents or malfunctions due to debris present on the tracks or on various sensors on the machine.

How do you choose the right air compressor?

Types of air compressors

Screw air compressors

The screw compressor uses two spiral screws that rotate within each other. Air is drawn between the spirals and compressed as they rotate.

The screws operate in sync, thus reducing the volume of air and increasing its pressure as it moves through the compression unit. 

The air is then directed to the storage tank via pipes and valves.

Piston air compressors

The piston compressor uses a movable piston that moves within a cylinder. 

When the piston moves upwards, the volume in the cylinder increases, and air is sucked into the cylinder via an intake valve.

When the piston moves downward, it reduces the volume of the cylinder and compresses the air inside it. The compressed air is discharged from the cylinder via a discharge valve and stored in a tank.

What are the differences between a screw and a piston air compressor?

The main differences between the two types of compressors are:

• Operating principle: The screw compressor uses 2 spiral screws, which rotate in sync to suck in, compress and discharge air, and the piston compressor compresses air through the up and down movement of a piston in a cylinder. 
• Energy efficiency. Screw compressors are more energy efficient than piston compressors, providing a constant air flow at high pressures with better long-term efficiency compared to piston-driven compressors.
• Durability. Screw compressors have a longer lifespan, making them suitable for intensive industrial use. They also require less maintenance than piston compressors.
• Noise. Piston compressors can generate more noise during operation than screw compressors, which are generally quieter.
• Costs. The initial costs are higher for screw compressors compared to a piston compressor. However, the long-term maintenance costs can be lower compared to a piston compressor.

Important criteria for choosing an air compressor

You need to have a clear perspective on the production you have or the application where you will use the compressor. 

Screw compressors are machines that need to be kept working. Used in industrial applications, they are designed for intensive use throughout a work shift. DANIBRUM technicians have encountered numerous cases in which compressors broke down because they were not operated according to the manufacturer's duty cycle charts.

Of course, flow and pressure requirements are 2 important elements, especially if you will use the compressor to power various groups of machines in your production line. It is very important that it can deliver the correct pressure, in order to protect your machines and use them at full capacity. Do not forget: if a piece of equipment is more affordable, that does not mean it is suitable for every activity. Take advantage of our free consultancy and make your purchases fully informed.

Maintenance and service. Again and again. This aspect, most often left for last, is extremely important. Let's assume you do not need service. You use the equipment correctly, following the manufacturer's instructions, but you need certain consumables (filters, oil, sensors, etc.). If your supplier does not have a trusted partnership with the machine's manufacturer, you may end up halting production over a simple sensor or a piece of information for which no suitable answer can be found. Spare parts stock and training received from manufacturers are important. We know this, and we work to have trained people and the widest possible stock of parts and consumables.

Air compressor maintenance

Like any equipment, maintenance extends the life of compressors. Checking the oil and replacing the filters on time is absolutely essential. ATMOS compressors are equipped with systems that notify you when filters need to be replaced, in order to prevent compressor failure.

Inspect periodically the belts and the connections of valves, hoses and other elements that could come loose. Because these are stationary machines, some connections may loosen due to vibration.

Check for oil or air leaks. If you notice a decrease in the overall efficiency of the compressor, pause and do a careful check. Preferably, this check should be done with a technician, via video conference, to diagnose and act on the problem correctly. 

Train your staff. Even if it is a seemingly simple machine placed in a corner of the workshop, every employee must know the basics about it: how it starts, how it stops, how it is cleaned, what unpleasant situations could arise, and so on.

Periodic maintenance services. Schedule regular inspections and maintenance carried out by technicians authorized by the manufacturer.

Conclusions

A compressor is indispensable to any production line, of any size, because, like life itself, air is vital for living and growing.