What you need to know about AM

Multiple lasers contribute to increased throughput. Here, four lasers work simultaneously across the build plate to maximize build speeds.

Additive manufacturing (AM) of metal parts is a game-changer.

The technology is seeing explosive growth and acceptance across many industries. Business leaders are scrambling to implement and leverage this revolution for competitive advantage. Staying current with this wave of change is a strategic imperative for manufacturers because the advantages over traditional manufacturing methods can’t be ignored.

Ask these questions to find the equipment that best fits your unique business needs.

1. What is the difference between processes?

The AM world loves acronyms. It’s next to impossible to list them all in a brief overview, so instead let’s focus on the most common acronyms related to AM metal processes.

The vast majority of metal printers in use today are based on powder bed fusion technology in which a layer of fine metal powder is spread across a machine bed. The selected regions of the powder layer are then fused to the layer beneath them and the process repeats layer by layer, until the entire part is built within the powder bed.

The melting is typically done with a high-power laser.

With that background, here is some industry insider insight: Common acronyms, including direct metal laser sintering (DMLS), selective laser melting (SLM), direct metal laser melting (DMLM), and laser cusing all refer to the same process.

Competing equipment suppliers use lasers and the same basic melting process, and the only difference is the marketing behind the name.

So if industry competitors use the same lasers and same technology, how do you compare them?

That’s where things get interesting. The major differences are how machines are designed and operated. These differences can accelerate or hinder your efforts to gain an edge on your competition.

Powder bed fusion technology layers fine metal powder across the machine’s bed and then fuses it to the layer beneath, until the entire part is built.

2. Does one size really fit all?

The industry-standard machine size for laser-based powder bed fusion machines historically has been a 250- by 250-mm platform with a build height of 250 to 300 mm. This size has stuck around for most suppliers, but not all. Read the specs and understand the difference that a slightly larger envelope can make for you.

In an effort to keep things simple, many suppliers take a one-size-fits-all approach to system configuration. That may meet your needs today, but be sure to think about this in both the short and long term.

Some factors you should consider are:

• How frequently will I be changing materials? Is this easy or difficult?
• Are there times when I would like to run small sample tests with potentially expensive materials? Is there a way to limit the material required without going to a smaller overall platform?
• Do I have options for the material used in the recoater blade? (This is an area to explore if fine details and high throughput are important to you.)
• Will I be building large parts that use the entire build envelope? Is there a way to add more powder if supplies run low during a large build?

3. How can I get there faster?

There are many factors to consider around the concept of getting faster results from additive metal processes. The time it takes to build a single part is probably the most typical reference point for comparing machines. This is a logical and useful number, but other factors also have an impact on overall system throughput.

As you move from single-part runs to low-volume production or larger batches, think through the following points and scenarios:

• How is powder coated on the build tray? Depending on system design, powder can be spread in both directions or only in one direction. Feeding powder in both directions can save hours of production time. A single build can contain 10,000 layers, and wasted seconds on each layer add up quickly.
• What options are offered for laser configuration? Lasers are the heart of the system, so if you have more lasers, you can produce more parts faster.
• How is material fed to the build chamber? Is the supply continuous or fed from an initial batch of material? Batch-fed systems can require the machine to be interrupted to refill supplies during a run, which slows down the process.
• All mechanical systems are going to have operating issues from time to time. Can the system you are looking at recover from minor errors without operator intervention?
• Are you able to tune system operating parameters to increase speed?

4. Who owns my operating parameters?

Proper operating parameters is the key to building successful parts.

Many factors, including laser power, scan speed, stripe width, and focus settings, are developed for each material and each machine. These parameters ensure acceptable quality over a range of part geometries. Parameter development is not a trivial process, and it is not an exercise for beginners.

As you move along the learning curve, however, some tweaks to baseline parameters are useful (or even necessary) to optimize build results. Some of the factors you might want to optimize are:

• Build speed.
• Surface finish.
• Porosity.
• Specific metallurgical properties.

To modify parameters, you first need to have an understanding of what the baseline parameters are. Second, you will need a set of tools to make the trial-and-error process as easy as possible. This may sound straightforward, but you will be surprised to find that it is not always so. This aspect of system design is where suppliers vary widely on business policies and the tools provided.

In some cases, parameter sets must be purchased for each material. These parameters may be locked to prevent you from editing them. Parameters may even carry annual licensing fees.

Other OEMs offer an open architecture for parameters, along with robust tools to help your development efforts. Make sure you understand the policy and feature sets around these parameters fully before committing to a supplier.

Parameter development and introduction of new materials may be critical to your success. Like for any piece of production equipment, the biggest gains will go to the shops that invest the time and energy to understand their equipment and how to optimize performance for a competitive edge.

5. What if I want to try new materials?

As a new user, the most common approach to ramp up quickly is to use materials and parameters supplied by your equipment supplier. This removes variables and speeds up the learning curve dramatically. As you gain experience, you may want to explore new options.

Material companies are making huge investments to develop new material variants specifically for the additive market. As you look to the future, it may make sense to know that you have the flexibility to seek new avenues.

Flexibility is rooted more in business policy than technology.

Be sure to discuss this with potential suppliers. Will they support your efforts by openly sharing experiences? Or will their business practices slow your efforts?

This issue is closely tied to operating parameters. If you are going to explore new materials, you will almost certainly be developing and enhancing operating parameters.

There are advantages in using a single source of supply for all aspects of AM operations (machine, materials, and software parameters). However, in a manufacturing environment, a “me too” strategy rarely creates a sustainable competitive advantage.

6. What are the hidden operating costs?

Additive metal machines have operating costs. These vary as a result of system design as well as business policies. The common costs are:

• Raw materials. It may be important to have choices for where you purchase materials. These choices will affect quality, differentiation in the market, and, of course, cost.
• Inert gas. The additive build process requires an inert, oxygen-free environment. That is maintained by a recirculated flow of argon or nitrogen. The amount of gas required is a significant consideration. Usage can vary by as much as 10 times between equipment suppliers, amounting to thousands of dollars annually.
• Annual licence fees. Knowing the fee, if any, for use of operating parameters on each material is paramount to understanding the cost of running AM equipment.

Other costs such as electrical power are fairly constant for all equipment (after all, they typically all use the same lasers).

7. What are my safety concerns?

Safety concerns fall into two main categories: powder handling and maintenance.

First of all, the powders used in this process are very fine and can contain particles as small as 6 microns. These are hazardous to breathe, so you must use proper safety gear, or personal protection equipment (PPE), whenever you are exposed to metal powders.

PPE is a start, but it can be improved greatly through system design features that minimize exposure to metal powder. Review the recommended sequences for loading and recovering powder and see how many points of concern exist.

Another important safety concern is maintenance of the filtration system.

The AM process generates particles and smoke that are filtered to keep the process running smoothly. Periodically the filters must be changed. Understand fully the steps of this process for the equipment you are considering.

Some designs expose you to dangerous particles in the filtration system. Other designs allow safe handling and passivation (neutralization) of harmful content in a sealed environment.

If you might be using reactive materials such as aluminum and titanium, powder handling concerns are amplified by a potential danger of fire or explosion. This is a real concern that many companies could overlook. Don’t make this critical oversight.

Why take chances? Look for a design approach the keeps employees and facilities as safe as possible.