The technology of waterjet cutting is very complex in terms of the variables that make up the operating costs of a machine. The aim of this article is to identify all the factors that affect the operating costs of a machine and to show their influence in relation to each other when the values of the parameters that characterize the variables change. It is not useful to give specific cost values as they are different for each machine. It is more important to show future investors how the price of services is made up and to make the recipients of services aware of where the prices proposed to them come from.

Factors influencing the WaterJet operating costs

The first dilemma is the question of the conversion unit for the cut. There are two common measurements: Cutting time and cutting length. Both conversions are not entirely reliable unless certain assumptions are made.

Cutting time - determining the price based on a given value assumed in a specific unit of time, e.g. PLN/h. The basic question in this case is at what speed the machine will cut. Knowing that a given element can be cut at different times, it is easy to guess that faster cutting will be accompanied by a deterioration in quality. So when comparing the price of two service providers, always ask for the same speed and quality classes.

Cutting by the meter - this conversion rate seems to be more accurate. But even in this case, the price should be given for a specific quality class. In this case, it should be noted that cutting a sheet half a meter wide costs just as much as cutting a complex part. The price per meter varies, of course, depending on the thickness and type of material.

The next point is the variables that influence the price for an hour or a meter of cutting. In both cases, the price components remain identical:

• Abrasive consumption - users of waterjet machines calculate the average amount of time it takes to consume a packet of garnet. The differences in abrasive consumption for individual material types and thicknesses are so small that it is not necessary to set multiple price thresholds,</li
• Service performance - even during the warranty period. This factor is constant, as it does not depend on the amount of work performed, and is difficult to estimate accurately,</li
• Spare parts that wear out quickly - especially the sapphire and the mixing nozzle. They have a certain service life, after which they are replaced,</li
• Electricity - consumed in proportion to the work volume. If you know the unit price, you can calculate the cost of cutting a specific batch of material,</li
• Water - the most important factor. The cost of water consumption is calculated based on the average hourly consumption. This depends on the model of your pump,
• Operator labor - this is a fixed cost that is independent of the work performed. This rate is set in a contract between the employer and the employee,
• Depreciation - this is also a fixed cost

When determining the price of services, the margin is also a component. It can have different amounts. It is usually determined depending on several factors:

• the size of the batch of material to be processed - the price can change as the size of the order increases,
• competition - the growing number of companies providing the same services can lead to a local drop in prices for these services,
• Seasonality - the occurrence of this phenomenon can lead to price fluctuations

Many factors contribute to the cost of operating a waterjet machine. This should already be considered when planning the investment. In particular, when planning the use of the machine, you should not forget to equip yourself with an appropriate amount of garnets and wear parts.

Each piece can be cut in five different cutting qualities, which have different prices. The different cutting qualities have to do with a so-called taper, where the hole on the bottom of the plate has a smaller diameter than on the top (side of the cutting nozzle). The reason for the taper is the increasing distance of the cut material from the nozzle. The energy of the jet is then lower and so is the cutting ability. With waterjet cutting, however, an inverted taper can occur, i.e. the hole at the bottom is larger than the hole at the top. This happens if the feed speed is too slow and/or the amount of abrasive supplied is increased. This phenomenon can be minimized by using a quality cut (higher grade).</p

It is important to determine the expected cut quality grade before starting to cut parts. When cutting services, the choice is always made by the person ordering the service. It is unacceptable that a customer accepts a sample part with a certain cut quality, but the actual batch is produced with a different cut quality.