Tooling is crucial to all stages of the powder metal manufacturing process.  In the simplest form, tooling can be described as the process of planning, designing, and engineering tools that are used to mold powder metal components.  To summarize the tool design process, we interviewed our tool designer Wayne Valentine.

Wayne joined the Atlas Pressed Metals team in 2006 and started designing tools in 2010.  Wayne brought with him over twenty years of die setting experience.  Wayne’s strong work ethic paired with his extensive PM knowledge and keen eye for design, make him a tremendous asset to the team.  While Wayne is originally from St. Mary’s, Pennsylvania, he now resides in Falls Creek, PA with his fiancé and family.  When Wayne isn’t designing tools at work he enjoys the open road on his Harley.  His love and passion for bikes was ignited when Wayne received his first dirt bike when he was a boy.  Since then he has enjoyed riding and hopes to one day attend the Sturgis Motor Cycle rally.

In this interview, Wayne walks us through the process of designing tools for powder metal components. 

What is the most valuable skill(s) that you learned prior to transitioning into your position as a powder metal tool designer? 

I was a die setter for 27 years. Knowing how the presses and tool components worked together has been very advantageous as a tool designer. I’m still learning every day, as there are always new advancements in molding components. When I first started in PM there weren’t multi-action presses like we have today. A tool designer had to make their tools work as a multi-level press. It was challenge!

When designing a tool set for a new powder metal (PM) engineered component, what factors do you take into consideration prior to beginning the design process? 

Initially, I look at the overall desired shape of the component along with its size and length, wall thickness, compaction ratios, and the levels within the press that are needed to make the component. The next consideration is the raw material that is being used for the component. Single level parts are pretty straight forward, but when you get into more structural parts you have to start thinking of how thin a punch is compared to the length required for compaction. I also have to consider the integrity of the tooling over the lifetime of the part as well as shape complexities.  As complexities and levels increase, the tools become more challenging and, often times, costlier. 

Pictured at right is an example of a basic set of compaction tooling. A basic set of tools include the die cavity (this is where the powder goes to form the most of the parts geometry), and upper and lower punches (to compact the geometry to a specified density, as well as ejection of the component). A core rod is included when an inner diameter is required.

What exactly do compaction tools do?

Compaction tooling involves taking a pre-determined “stack “of metal powder that has been gravity fed into a die cavity that is then compressed under high pressure to form a net or near net shape part. With the materials that we now have available, we can produce a component to desired shapes much faster than other metal forming techniques such as machining, casting or stamping. PM tools also allow us to mass produce components off a single set of compaction tools, making it a much lower cost option than other metal forming techniques and still gives our customers the same integrity they would have machining the same components. The compaction tools actually create the green (pre-sintered) part from the powdered material.

Please explain compaction ratios? 

This is the amount of material requires to make the specific length of the component under high density compaction. Typically, the ratio is a 2 to 1 fill meaning that if your part is 1” in length you will need 2” of fill. In a single level component this is easy to see but multilevel components require the 2 to 1 fill for each level in the part and therefore each level requires its own tool member.

What is your process for creating a PM tool set design?

Each tool set has its own set of requirements and challenges, but the basic process I follow is:

1. What size press we will need to compact the component?
2. How many levels will it take to produce the component?
3. What are the wall thicknesses of the component?
4. What are the different lengths on the component to see if there is enough compaction ratio to produce the component?
5. Are there shapes that are not PM friendly like bevels, chamfers, and radii that will not hold up will on the tools.

Do you utilize the same process for designing both simple and complex PM tools?  

Complex components and single level components use similar design thought processes. Complex component tooling design is more demanding due to complex shapes, intricate features and sizes but the design process is basically the same as straightforward single level components.

When looking at the big-picture approach to tooling, what creative solutions do you employ during the tool design process to ensure that the project is as cost-effective as possible?

We are always looking at the most efficient way to produce a component that will deliver the performance our customer needs. At the outset of a tool design, we meet as a team to discuss the compaction process including the set-up time for the press, handling of the component through the process and any automation that may be needed. We also outline the sintering plan and identify other secondary operations that are required to complete the component.  All of these processes have an influence on the tool design.

Pictured at right is the tool set for a single level component. This tool set uses a die,  upper and lower punches and the core rod. The final components are also pictured.

For the actual design and manufacturing of the tools, I rely on our in-house tool shop for input.  Our Atlas tool makers are experienced in tool and die making. Typically, the initial set of tools for a new component is made from tool steel.  The selection of the grade of tool steel is dependent on the components’ application. Factors such as hardness, toughness, wear and heat resistance as well as availability and cost need to be considered.  The goal at this point, is to manage the balance of these factors in order to pick the grade of tool steel that will give the best performance. Equally important is the input from our metallurgical lab. We at Atlas are fortunate to have a very well-developed data base of our materials (powder), and the specific growth curves under varying densities and sintering conditions. This information is extremely important when designing tools.  In many cases, once the initial set of tools is made and tested in the compaction process, adjustment are made, including the use of carbide, to further increase the life of the tools. Targeting the dimensional requirements of the finished component requires the application of a “tool” factor (compressibility and growth) in the production of the tools themselves. It is a bit of an art.

There is a lot of team collaboration that goes into designing powder metal tools. Our common goals are to 1.) create cost effective tooling to ensure that our die setters will be successful and efficient in setting up the press, 2.) create a part to customer and Atlas quality requirements, and 3.) make the tools robust enough to last through the life of the component. 

Additionally, we have skilled tool makers in our area who produce the majority of our new tools and on occasion, I do rely on outside tool design resources for assistance. Here in central Pennsylvania, we have strong relationships with the tool makers. Often, we assist each other.

Pictured at left is the tool set for a multi-level component. This tool set uses the die, three upper and lower punches and the core rod. The final mulit-level components are also pictured.

Is the typical die punch clearance 0.0005 inch. How can we describe that to the average person – how thin is this?

The punch to cavity clearance is very important as it is critical to hold tight tolerances so the fine grains of powder do not fall through the spaces in the tooling.  If this occurs, significant damage may occur and the life of the tool may significantly be reduced.

Typical components under 1¾ inch OD (outside diameter) have .0005 inch per side clearance. This also depends on the geometry of the part as well.  As you get bigger in size you’ll need more: 2-3 inch OD will need .0007-.001 inch per side clearance or sometime even more. For larger components the clearance is more like .002 inch per-side. We evaluate the tools after the initial molding run to see if we need more or less clearances. To describe how thin .0005 inch is - a human hair is .002 inch so .0005 inch is one quarter (1/4th) that size.

Knowing that PM tools often produce a relatively large number of components over their life, what are the key factors to improving/increasing the life of a tool set? (design, maintenance, etc.)

Each component presents a learning curve when estimating tool life. Everyone wants their tools to have longer life. It is difficult to predict how tools will react to the strains that they are going to withstand.  We start with raw materials (powdered metal) that we believe will hold up to the compaction pressure and go from there. After evaluating how the tools performed we might go with a harder material or a softer material or even use coatings depending on how the tools wear and deflect. There are times we change the geometry of the punch base to withstand loads.   

In conclusion, approximately how many tools have you have designed throughout your career? 

If I had to guess, I would estimate that I have designed around 575 tools. In addition to designing tools, I also redesign tools that support technology innovations (with the development of new materials), press advancements, sintering condition improvements, and processing upgrades. 

Quite a great career – thank you, Wayne.