Growth and interest in metal Additive Manufacturing have never been stronger. Previously, companies might buy one or two systems for qualification and testing. Now, companies are buying many at a time for manufacturing in large quantities. In September 2017, SLM Solutions reported a sales contract of fifty metal AM machines to a customer in China, amounting to €43 million. This was followed at formnext 2017 with the announcement of an order for a further twenty machines to an Asian customer valued at €37 million. Other machine manufacturers are no doubt also doing brisk business.
Most of the metal AM systems on the market are based on Powder Bed Fusion (PBF) technology. Major companies in this business are EOS, GE, Renishaw, SLM Solutions and 3D Systems. Among the lesser known companies that offer metal PBF machines are Additive Industries, AddUp, Bright Laser Technologies, Farsoon and Realizer. In preparing Wohlers Report 2017, Wohlers Associates identified twenty-eight companies worldwide that produce metal PBF systems. Fifteen are in Asia and eleven in Europe, but only two in the USA. One US company is General Electric (GE), which entered the business through its acquisition of Arcam and Concept Laser – both European companies. The other is 3D Systems, which entered the metal AM market through its acquisition of Phenix Systems and LayerWise, also two European companies.
Metal AM machines
The list prices of industrial AM machines are not as easy to get as one might think. We have obtained and published base prices of metal AM machines in Wohlers Report 2017. They range from about $115,000 for a relatively small and basic configuration to nearly $1.9 million for a machine that can produce parts as large as a full-scale V6 engine block. With so many companies now offering their own systems, the pricing and number of options is extensive and increased competition are starting to force prices downward.
Sieving equipment for powder recycling is an important part of a metal AM system. Some machine manufacturers will bundle sieving equipment with the price of the machine. To avoid unpleasant surprises after a purchase, it is important to understand what is included with the machine and what isn’t. It is not unusual for customers to learn that something is missing only because they failed to ask the right questions. If you are unaware of some of the process steps and ’hidden’ costs, it is impossible to know what questions to ask.
Most metal PBF systems operate in an inert atmosphere to reduce the possibility of contamination from gases, such as oxygen and carbon dioxide, in the air. An inert atmosphere helps to ensure that air molecules do not change the physical properties of the parts being produced. Argon gas, nitrogen gas, a vacuum, or a combination of these is used to eliminate the unwanted gases. The cost of argon gas can exceed $12,000 per year for one system; the actual cost depends on the local price of the gas, the way in which the AM machine uses it, and the size and amount of time for which the machine is used. If nitrogen is used, the gas can be obtained either from gas bottles or from a nitrogen generator.
Metal PBF systems operate best when ambient temperature and humidity are maintained at the levels recommended by the machine’s manufacturer. Air conditioners, humidifiers or dehumidifiers are usually necessary. Their initial cost can be in the range of $10,000, but this amount can vary greatly depending on the size of the space where the machine is being operated.
Your building may require alterations to accommodate a metal AM system. In some cases, doorways may need to be widened or walls removed so that the machine can be moved into place. Proper ventilation is also necessary to reduce hazards associated with materials in the form of fine powders. Machine weight is another consideration. In a recent case, a machine’s five-ton weight required structural changes to the factory floor. Here, steel plates were installed to spread the load to an acceptable level.
New gas lines and electrical changes are often required when installing a metal PBF system. If using or storing reactive metal powders, such as aluminium or titanium, sprinkler-based fire extinguishing systems should be disabled because metal powders can react dangerously with water.
If the machine is operating in a relatively small, enclosed space, and argon gas is used, it may be advisable to install sensors that show the level of gases, such as oxygen, in the air. If an argon gas leak occurs, it could quickly suffocate the people in the room.
Accessories and other costs
An industrial compressor is required and can cost $30,000. A sand blaster is needed to clean the powder attached to the parts and can cost $12,000. A shot-peening cabinet is also useful for improving the surface finish of the parts. It is similar to a sand blaster, but uses larger media, often in the form of small ball-bearings, to flatten the high spots of a rough surface. They can cost $15,000. Industrial vacuum cleaners are required and can cost $18,000. It is very important that they are intrinsically safe and can be used with reactive powders.
A heat treatment furnace can cost in the range of $15,000–$30,000. One used for titanium can cost $100,000. Equipment is needed for removing the parts from the build plate. It can consist of a standard band saw ($10,000–$25,000) or a wire EDM system, which can cost $50,000–$200,000. Electricity can cost $3,000 annually, depending on local pricing. Hot Isostatic Pressing (HIP) is used to eliminate porosity and microcracks in metal parts. HIP is usually outsourced, but it should be budgeted for aerospace and certain other types of structural parts. To buy a HIP system, plan to spend $1.5–$3 million.
Software licensing fees can cost in the range of $3,000 annually, but this too can vary widely, depending on the design and AM machine software modules purchased. Annual maintenance contracts for an AM machine can range from $10,000 to more than $30,000, depending on the level of service required. Maintenance contracts extend the warranty beyond the first year, which is often included in the purchase price. The cost of filters for a metal PBF machine can be $30 each, but they can go as high as nearly $7,000 for the type needed for some production-ready systems. Other consumables include build plates, recoater blade wipers and lasers.
Safety equipment is required to protect the operator from exposure to the metal powders. This can range from a few hundred dollars for gloves and face masks, to several thousands for full body suits with built-in air filtration.
Talent and labour requirements
Operation and part finishing to support one metal AM machine can cost $150,000 annually. Postprocessing of parts can be labour intensive and usually begins with the removal of powder surrounding the parts when the build is complete and has cooled. After most of the loose powder has been removed, the parts and support structures – still welded to the build plate – are removed from the machine. Additional powder is removed from holes, cavities, and other areas using hand tools, compressed air and blasting.
The build plate, with parts and support material, is then placed into a furnace for thermal stress relief. Skipping this step can result in the warping of parts when removing them from the build plate due to residual stresses built up in the parts. After stress relief, the parts and support structures are cut away from the build platform. The support material is then removed from the parts using a combination of manual cutting, milling, grinding and other methods.
Some parts undergo HIP. Further heat treatment is used to strengthen and harden parts. Surfaces that require precise dimensions and flatness are usually CNC machined, which is an expense that also needs to be considered. Parts may undergo abrasive tumbling, electro polishing, or one of a number of other methods of surface treatment. One of the final steps is inspection.
One of the most important considerations when purchasing a metal AM system is the need to design for Additive Manufacturing (DfAM). Good DfAM can result in a reduction of support structures, material, part weight, inventory, maintenance, and assembly labour, leading to considerable cost savings and a product that performs better and is more competitive. Quality hands-on DfAM training can cost $3,000 or more per person for a three-day course. Consider also the time that it takes for a designer or engineer to practise what they have learned and to become productive.
While applying DfAM, it is important to consider build orientation. Building a part on its side, upside down, or at an angle can reduce the need for support material and its removal, which can take days of time, effort and skill. Clever DfAM techniques can also reduce the need for support structures. Proper packing of parts in the build chamber is important to benefit as much as possible from the economy of scale that comes with PBF processes.
Due to the cost of producing metal parts by AM, most systems are purchased with the goal of using them for production applications. It is not uncommon to build parts multiple times before getting them right. This can be expensive because a single build can take days, even a week or longer, to complete. Heat distortion is a major cause of problems in production; software tools from 3DSIM (now owned by Ansys), MSC Software, Autodesk Netfabb and others help to predict distortion and optimise the number and location of support structures.
Metal PBF systems come with a number of safety considerations. One of them is the use of reactive powders, such as titanium and aluminium. Both can ignite, burn, and even explode under the right conditions. In fact, fine aluminium powder is used for explosives and pyrotechnic displays. It is important, therefore, to take special safety precautions when using these types of powders. At minimum, a D-class fire extinguisher is required. Storage of powders, especially in large quantities, also comes with special considerations and can be expensive.
Many types of metal AM systems are available worldwide, with Powder Bed Fusion being the most popular, by far. The list of costs and considerations can be overwhelming, and even shocking, when purchasing a system without prior knowledge of them. It is important to research the metal AM systems available and to understand the differences between them, and to learn about and fully understand the need for ancillary equipment, tools and skills, as well as the many process steps required to produce quality metal AM parts.
Olaf Diegel and Terry Wohlers Wohlers Associates, Inc.
The authors thank Simon Marriott, an AM expert in Australia, for his valuable insight and contribution to this article.