This is the cost of the material in the part plus its support structure and waste. In resin printing you must include the cost of the solubilised polymer in the liquid waste. The cost of the part plus its support structure will be available directly from the slicing software. It is important to assess whether the unused printing material is still viable for use, as both powder and photopolymer can deteriorate by being adjacent to polymerised elements. One of the largest errors in polymer printing costings is from waste material carried over to the wash solution, which is rarely accounted for accurately, either in its lost material or its subsequent disposal costs. The best way of making an accurate calculation is to make a lot of the same type of parts, know the resin consumed and the weight of saleable parts, and divide the two, but this is rarely possible. It is practical to weigh the cured material removed from a resin recycling system where the solid material can be polymerised and weighed, with the liquid being reused. Photocentric recommend the use of these systems for both environmental and cost reasons. Assumptions made on the amount of polymer in the wash by measuring the increase in specific gravity of the cleaning fluid are rarely accurate. In SLA formats less resin is wasted in bottom-up rather than top-down as the platform largely drips clean of resin during the printing process.

Labour costs are hard to calculate accurately because most 3D printed parts are different. Total labour involvement must include both the cost of designing (Design for Additive Manufacturing) and the direct labour in the part and processing costs. In prototyping most of the cost is incurred in the front end on expensive computer operators as opposed to the print operators. The knowledge of how to orientate, support, hollow, drain hole and texture parts to ensure print success is not yet available at the click of a button on a software program. These skills are expensive, but the alternative of enduring the randomness of print failure is even more costly. In the case when the process and customer intent are aligned allowing scale to be achieved with digital mass manufacturing, then the design costs can be amortised to almost nothing. The critical variable element in the manual tasks related to platform transfer, part removal and part finishing is the amount of labour required in the finishing stage. Some parts can be simply thermally shocked off the platform, undergo a simple QC step and be ready for use. However, if parts require supporting, the removal of those supports and the sanding of the artefacts will be the most time-consuming and therefore expensive part of the process. There may be painting required as well further adding to the costs. The creation of automated additive manufacturing processes is key to reduction in labour.

Running costs are an area that manufacturers are rarely open about the costs involved. With energy a significant factor in the cost of running any business it is important to look at the amount of energy your large format 3D printer consumes. In LCD 3D printing, the energy is mainly consumed in the cure unit, with little used in the printer and hardly any in the wash. LCD printing then has three running costs, electricity costs, vat film, resin cleaner and its disposal. New advances in vat film have reduced the need to change it. The resin cleaner will have a given life dependant on how much polymer is solubilised in it. Other consumables which should be taken into consideration are Isopropyl alcohol for cleaning the finished part, sandpaper, wipes, gloves, etc. Additional post process techniques such as tumbling, sand blasting or spray painting all have running costs. Photocentric recommend the purchase of a resin recycling system which generates solid material that can be fully hardened in sunlight and solvent that can be fully reused. It is also possible to separate the rinse water from solid polymer to enable them both to be disposed of safely and cost-effectively.

Photocentric amortises equipment over 5 years with a residual value of 30%. The method of amortisation depends upon an assessment of whether you will still be able to viably use the print process in the future and whether the machinery will still be functional that far into the future. You also have to assess how much of the year will you be able to use the machine for estimating the percentage of the year the machine can operate and also whether you have work for it. Photocentric bases its amortisation on the reliability of the LCD screen illuminated by daylight which is supported by their use of printers for over 5 years in Photocentric’s Print Farm with little issue. You may for instance be able to print longer prints through the night to improve utilisation. All Photocentric printers are equipped with LED power supplies that have over-current, over-temperature, and over-voltage protection making them safe to operate overnight without human intervention.

With some technologies, maintenance can be very expensive making machine reliability over its life a critical factor in determining amortised cost. Over time, maintenance costs can escalate and make repairing the machine no longer viable. Large format machines often must be repaired on-site by trained engineers from the company that sold them to you. Parts can require frequent replacement; software can have annual subscriptions and on-site servicing can be expensive. Repair can be seen as a significant income generator, bizarrely making a machine that breaks down frequently more lucrative to the manufacturer than a reliable one. In resin printing, the lamps in digital light projectors need replacing as do the light engines in lasers. In LCD printers’ screens illuminated with visible as opposed to UV light will last for many, many years, UV illuminated screens burn out, but their replacement costs are very low.