Hybrid Additive Manufacturing Improves Debarking Knife Tip Strength and Production Efficiency

Manufacturers looking to adopt additive manufacturing (AM) aren’t always looking to completely replace traditional subtractive processes. Instead, they might be looking for a hybrid manufacturing solution that offers them the best of both methods. That was the case for Nicholson Manufacturing (Sidney, British Columbia, Canada) when it started looking for a more functional AM software that would enable it to make the knife tips for its ring debarkers more rugged and long lasting.

Nicholson Manufacturing has long been an innovator in the forestry industry. In the 1940s, the company aimed to modernize the forest industry when its founder and owner Bill Nicholson designed and built lathe and rosser head-style debarkers to replace manual debarkers, which until that time was the only available technology. Manual debarking, as it sounds, was a tedious and backbreaking process.

In 1951, Nicholson built his first whole-log mechanical ring-type debarker, which feeds a nonrotating log through a multitool rotating ring. The technology proved successful and is the model for the company’s current product line. Nicholson designs and builds ring debarkers for lumber facilities throughout the world. While early ring debarkers had speeds of 80 to 100 feet per minute, the technology has improved to current processing speeds of more than 650 feet per minute.

Today, the company continues to innovate — all the way down to the debarkers’ very knife tips — which are an essential part of the debarkers and which are subjected to extreme wear and high impact during the debarking process. To strengthen the knife tips, the company began looking at using both subtractive and additive manufacturing for a possible hybrid process.

CNC Machinist and Programmer Steve Cracco is a 36-year veteran of Nicholson Manufacturing. After a decade away from the company, he returned and was tasked with investigating the possibility of bringing AM to the shop floor with new software. “When I came back to Nicholson, the management team wanted me to go to additive machining, which is something totally new for everybody,” he says.

Cracco says that adopting the technology to fit Nicholson’s hybrid application criteria first required extensive research and analysis by its R&D team. “We did not have a software system that could do what we wanted to do — additive plus machining — so we hunted around and found a solution with APlus,” Cracco adds. “It does additive machining and works only with Mastercam.”

Mastercam APlus is a specialized add-on designed by CAMufacturing Solutions Inc. to unlock hybrid manufacturing for current Mastercam users. Cracco was already familiar with Mastercam CAD/CAM software having used it during the 10 years he was gone from Nicholson.

Due Diligence

Nicholson Mechanical Designer and Draftsman Jay Hale has been with the company for 11 years. As part of the R&D division, he leads Nicholson’s additive manufacturing MLX project. Before investing in the AM piece of the CAM/AM puzzle, Hale compiled a comparison chart of five additive software systems, examined past machining strategies and assigned weights to features in relation to Nicholson projects. Requirements included North American support, repairs, modeling and superior axis control. Each requirement was assigned a point weight and then scores were totaled.

“I did an extensive analysis of the available software and compared all their features and gave them fancy ratings,” Hale says. “I sent that off to the Mastercam team so they could have a look at it. It came down to the fact that we only had to train Steve (Cracco) on the additive side, not the entire system. And the other AM software systems did not have all of the features we needed. APlus was the obvious choice.”

The APlus solution is designed to work seamlessly with the CAD/CAM software’s mill, lathe and routing solutions, and even runs right in its normal interface. Additive tool paths are often based on CAD models and directed by CAM tool paths, which determine how much material to put where and when. APlus users can program, backplot and simulate AM tool paths the same way they do with traditional subtractive tool paths.

APlus works with directed energy deposition (DED), which is often used for metal part repair or to add material to metallic substrates. It also makes it possible to switch back and forth between additive and subtractive functions. By alternatively adding and cutting away material during the manufacturing process, users can create incredibly complex internal features on their parts.

System Integration

Nicholson Manufacturing has been using the CAD/CAM software since 2022 with the APlus software fitting well with the company’s manufacturing strategies because it supports programming and simulation of AM processes in Mastercam. Its seamless integration into the CAD/CAM software delivers the benefits of CAM and AM with the flexible AM technology optimizing tool paths and features for DED.

Since adopting AM capabilities, Nicholson has used it to create those rugged knife tips for its debarkers. The AM machine adds durable layers to wear surfaces of the tips, hard surfacing the long-wear parts. Nicholson says durability is a key feature of its debarker knives and tips.

“The knife tip is located at the business end of a debarker,” Hale explains. “That’s what takes the bark off the log. Each tip needs to be incredibly tough, incredibly hard. Imagine the inside of a debarker. Those knives wing around at a couple hundred rpm with a log firing through it at 500 feet per minute. It’s bad in there. It’s violent and its abrasive — and that’s on a good day if the machine is processing only one log at a time.”

A typical debarker contains between three and six knives. Nicholson manufactures five models of debarkers and supports many other models that it sold over the years. It has approximately 100 part numbers for knives but is concentrating on a dozen before branching out and developing more.

Replacement Parts

Given the extreme conditions surrounding lumber processing equipment, replacement parts are always in demand. Depending on environmental factors and facility capabilities, some lumber mills can get a week’s worth of use out of their knives, while other mills can get six months.

“Every mill is different, every tree is different and every application is different,” Hale says. “Some logs carry sand out of the field. Some sit in tidal water, so they roll around in mud and pick up rocks. Good luck getting a couple weeks out of those knives, but these new ones can take it.”

Hybrid Manufacturing Process

At Nicholson, the first step in creating a knife tip is using Mastercam to machine in-house fixtures. After parts are machined, they move on to the AM step in which a laser distributes and melts powdered composite material onto the knife tips with the number of layers varying by part. Together, Mastercam and APlus run the entire additive layering process.

Cracco programs the additive part, specifically the additive deposition passes. Nicholson uses a Hybrid Manufacturing Technologies fiber laser bolted into a Haas VF7 to print and subtract in the same setup. A deposition head can be selected just like any other tool so an operator can easily go from cutting to printing. A custom manifold lowers next to the spindle and docks with the deposition head, which delivers the powder and laser energy.

Nicholson’s biggest struggle with its previous AM software was time. Mastercam and APlus brought programming time down from days to hours. Cracco can program one tip and program the tool to make five passes around a fixture. “Mastercam Pattern lets me program five tips at a time, not five individual tips,” he says. “So, I program one tip and Mastercam multiplies it for me. When I do multiple parts, I’m saving huge amounts of time.”

Hybrid Benefits

For a company that manufactures thousands of knife tips each year, the overall time savings provided by CAM and AM is substantial. Also, the CAM/AM software combination gives programmers and machinists more creative freedom than what previous AM software offered. The company says APlus also helps prevent machine downtime because operators are no longer required to print 90 degrees to the surface, which can cause damage from reflected laser energy and powder entering back up into the head.

“Now we have axis control, which is incredible. A game changer, really. If you don’t control how the part is oriented to the head, the laser can reflect up and melt the powder before it has a chance to get out of the nozzle and clog it,” Hale says. “With a combination of additive and subtractive technology, we’ve really subverted the fundamental laws of manufacturing — better, faster, cheaper. We used to have to pick two. Well, I’m not picking two. We’re having all three.”

Using 3+2 machining on the Haas VF7, Cracco uses Mastercam features to tilt the part 10 degrees on the trunnion and directs movements in the X, Y and Z axes. APlus tells the system when to fire the laser and how much powder to deliver. CAM and AM software work in concert to make one program that runs the entire process via G-code.

“Our previous additive software couldn’t do what we wanted it to,” Cracco adds. “One of the biggest issues was axis control. I couldn’t control how the head was pointing to the surface. With APlus and Mastercam, I have no issues. Mastercam has always had those axis control features, but for the additive part, we couldn’t find a program that would utilize them until we found APlus, which uses everything that Mastercam does. That’s the big plus.”

With its previous AM software, Nicholson had limited printing strategies. Now, the company has more options for laying down layers. Machinists can print parts with Mastercam and APlus for current jobs and future applications. With the success of its newly improved MLX knife tips and cleaning bars, Nicholson Manufacturing plans to use CAM and AM technology to create even more parts, such as knife arms and feed roll inserts.

“If it is a part that wears out and needs hard surfacing, we can probably figure out a way to improve it,” Hale says. “Our field tests with knife tips and cleaning bars have been promising. We are planning to develop improvements on the knife arms and other wear parts.”