Ontario mouldmaker optimizes conditions for hard-part turning

Akromold specializes in producing custom moulds for various industries, including pharmaceutical, power distribution, automotive, water distribution, and general industrial. This component is produced using D2 tool steel hardened to 56 to 58 HRC and measures 6.5 OD by 5.8 ID by 1.625 in. long. It is produced using only one OP1 with twin-spindle part transfer. Images: Akromold

In the 1950s many European toolmakers in southwestern Ontario were employed by Champion Road Machinery. For a while, during downtimes, it produced rubber moulds for companies in the surrounding region as it had a well-equipped machine shop and the talent to manufacture high-quality moulds. However, when primary business picked up, the company decided against making custom moulds beyond its own needs.

This caused the many shops that came to rely on Champion’s moulds to look for alternatives. Several former customers reached out to the toolmakers at Champion to see if they’d be interested in branching off and starting their own shop. Ernie Tafeit and two others decided to embark on this new path and launched Akromold.

With a small facility located in Goderich, Ont., the trio primarily focused on building moulds for the rubber industry designed by the customer. Over the decades, the shop grew in both size and number of employees. In the late 1980s Tafeit decided to retire and reached out to the shop’s superintendent as well as a tooling engineer at the shop’s main customer, Standard Products in Mitchell, Ont., and the duo decided to buy the company.

With Herb Haas and Terry Pellar at the helm, the shop shifted to a design and build model while still focusing on moulds for the rubber industry. The two men branched out, expanding the customer base into the U.S. and modernizing the facility with CNC machines and an in-house design department. In 2010 Haas sold his share to his son Rick, who co-owns the shop today with Derek Langtry, who joined the company in 2017, and longtime owner Pellar.

"We’ve just continued to grow the company and expand," said Langtry. "Our business today is primarily exports. We export 40 per cent to Mexico, 50 per cent to the U.S., and 10 per cent remains in Canada. We specialize in custom moulds for various industries, including pharmaceutical, power distribution, automotive, water distribution, and general industrial components for companies like Caterpillar and Cummins. About four years ago we were approached by the main suppliers to Bruce Power to manufacture high-end components for the nuclear reactor refurbishments. That’s our only non-mould work."

Across two facilities the shop employs approximately 35 people, 26 of whom are ticketed tool- and diemakers. The 22,000-sq.-ft. main shop is primarily for milling, assembly, and grinding operations and has over 20 milling machines, half of them 5-axis. The second 12,000-sq.-ft. shop focuses on turning as well as quality and includes five lathes, a few saws, and a metrology department.

"All of our machines are DMG Mori machines," said Langtry. "We are also very big into automation and standardized workholding. We use FCS systems for all of our workholding, which allows us to take one job off of a machine and put it on another easily. The setup is basically 100 per cent repeatable. It’s not dependent upon the machine model. What we feel really differentiates us is our engineering expertise in our field. And the fact that we have three tryout presses. So, any of the moulds that we build are 100 per cent tested at our facility and approved by our customers prior to shipment. It really allows us to export tools far distances worry-free because they’ve been 100 per cent debugged prior to leaving our facility."

Hard-part Turning

Akromold works with a variety of materials, including hardened 420 stainless steel, along with A2, D2, S7, H13, and O1 tool steel in hardness levels up to 62 to 64 HRC.

"A big challenge with hard-part turning is finding the optimal conditions to keep parts accurate while removing a lot of material in a hardened state," said Lance Bedard, plant manager, tool- and diemaker. "It’s so important for parts to keep their true form. Another big challenge when you deal with hard-part turning is maximizing tool life."

Both Langtry and Bedard agreed that clamping and workholding is a significant consideration. Most of the components are roughed out first, then sent out for heat treating. When they are returned and the hardened workpieces are being chucked, there can be no stress or deformation on the part. If there is, it becomes almost impossible to net out the exact shape of the part during hard turning.

All of the machines in Akromold’s shop are from DMG Mori, including five lathes. The shop is focused on bringing automation and standardized workholding to the shop floor.

"Once it’s unchucked or unclamped, you definitely don’t want the part to spring back to its original shape of the pre-heat-treat process," said Langtry. "You really have to be cognizant of how you hold the part and where you have to leave extra stock on for holding. Are your clamping forces evenly distributed around the part? You really need to make sure those clamping forces aren’t adding any distortion, because if you machine the part with distortion, it’s going to come out of your workholding with that distortion."

Bedard added that you shouldn’t be afraid to make your own custom workholding so that you can control how evenly the clamping forces are distributed and how the part is supported.

"If you are reliant on workholding designed for general machining, you’re not going to have a very high level of success," he said. "When you are machining parts in a hardened state, the sharpness of the tools will also make a significant difference in the success of the part. If the tool is dull, you will end up putting stress into the part as you enter finishing operations. With so many different variations of workholding and tooling, tool geometry will make a difference in what kind of stress you’re putting into the finished product."

Akromold uses a range of tooling because most of its work is custom and high-mix/low-volume production. The geometry of tooling depends on the integrity of the part. For parts that are very unstable or thin-walled, the shop will work with a much finer geometry. However, if the component is stable and strong, the shop will use a strong type of geometry with a bigger nose radius or something of the like.

"The more stable the part, the higher the cutting force it can handle without distortion" said Langtry. "If it’s a very unstable part, you have to be very careful with your cutting forces. Choose a cutting tool with geometry that minimizes those cutting forces during machining. Otherwise, you will start to see distortion. There is also a lot of variation in speeds and feeds depending on the type of material we are working with. The integrity of the part also plays a role, so for thin-walled parts, you definitely want gentler speeds and feeds. Allowing the part to not have any external stress is imperative in hard turning. It couldn’t be more important."

Study First

One of the reasons Akromold is so successful in its operations is that it has taken the time to do many studies upfront to learn about part distortion.

"It has been well worth our time to explore how much parts distort when they come back from heat treating and how much sacrificial stock is needed for proper hard-part turning," said Langtry. "You could err on the side of caution and leave more material than you need. If you perform a study upfront, you may find you need to leave only 0.01 to 0.015 in. for a hard-turning operation. Without the study, you may have left 0.04 to 0.05 in., which doubles or triples your machine time and your cutting tool expense."

Optimizing the Process

Akromold has developed several strategies over the years to optimize its turning operations. For hard-part turning, particularly in the finishing stage, a very finite window of tool life is available, but that doesn’t mean the tool cannot be used for other operations. The team has determined that these tools can be migrated to roughing and semi-roughing operations for parts after heat treating.

"For example, we take our finishing cutters from an OD process, and maybe they’re not good for finishing anymore because we need to achieve a certain surface finish or a more consistent diameter size," said Bedard. "Just because they don’t achieve that surface finish doesn’t mean they can’t be used for a roughing process. This allows us to optimize the tool life in the CBN [cubic boron nitride] inserts we use and increase actual cutting time."

Pushing processes to the limit and finding new and creative ways to get the most out of its tools are just a few ways that Akromold is staying ahead of the curve.

Working with Sandvik Coromant for its tooling needs, Akromold has developed a number of strategies to maximize its cutting tools. The shop values partnering with its vendors and relies on their knowledge and experience to optimize its processes.

"One thing that we see or consider a misconception is that CBN inserts are only capable of certain things and that they have a limited cutting range," said Bedard. "And although CBN isn’t a new thing—ceramic tended to be preferred for hard-part turning—advancements have made CBN the way to go. You shouldn’t be afraid to take a cut with CBN because technology has come so far. That’s definitely been a big change."

Choosing a CBN insert with a chipbreaker also has been very beneficial for the shop, especially for parts that don’t have good structural integrity. These inserts put a lot less cutting force on the part than a tool without a chipbreaker.

Akromold also understands the importance of workholding as it relates to hard-part turning. For the shop, aluminum jaws on all chucks is definitely the way to go for the projects and parts it manufactures.

"If you can’t find what you need or are looking for in a catalogue, don’t be afraid to make these components yourself," said Langtry. "One other thing that we’ve had very good success with are damped boring bars. If I were to give advice to somebody looking into this technology, I would say don’t let the cost of these tools scare you because the benefit of them far outweighs the cost.

Building Relationships

At Akromold the relationship between vendors and the shop is an important one. Langtry noted that his vendors are incredibly knowledgeable about their products and have been a big help when the shop has questions.

"It really does pay rewards to have your vendors involved in your development upfront because they can avoid a lot of pitfalls that you may encounter because of experience that they’ve gained and knowledge they have," he said. "We really like to consider other vendors partners, and we have very good relationships with them. And it does help in the development of your processes."

Bedard added that it can be somewhat challenging to ask for help. As a trained tool- and diemaker, he often wants to find his own resolutions to challenges.

"Toolmakers tend to be proud individuals and they sometimes don’t like to take help," he said. "That is something I personally had to get past. People generally love to show you what they know, they’ve seen a lot, and they have a lot to add. And if you are open to letting others, whether it’s fellow workers, vendors, or experts in the field, come and show a new product or a new process, there’s a lot to be gained by setting your pride aside."

Associate Editor Lindsay Luminoso can be reached at lluminoso@canadianmetalworking.com.

Akromold, akromold.com

Akromold uses its hard-part turning strategy to produce these bearing sleeves in A2 tool steel hardened to 56 HRC. This component has undergone OP1 of three operations and will measure 7.315 OD by 6.195 ID by 8 in. long when finished.