When veteran smoker manufacturer Cookshack was looking to improve production of their popular PG 500 pellet grill, the company called upon the Oklahoma State University New Product Development Center and the OSU Applications Engineering Program, funded by the Oklahoma Manufacturing Alliance, to help streamline the manufacturing process.
“It is important to us to build mutually beneficial relationships with small- to medium-sized Oklahoma manufacturers like Cookshack,” said NPDC Director Robert Taylor, Ph.D.
The long-term relationship between the NPDC and Cookshack allowed NPDC intern Jake Rowland, a mechanical engineering senior at Louisiana Tech University, to become involved in the production of the PG 500 pellet grill. According to the project impact report, the NPDC sponsorship of Rowland’s salary saved Cookshack 534 engineering hours.
“Probably two to three weeks before I started working with Cookshack, they shut down all production on the PG 500 and brought in Rajesh [Krishnamurthy] to fix the issues,” Rowland said. “At that point they thought the issues were more in assembly. So, Rajesh set up an assembly line, work cells and a good distribution of labor for the PG 500 manufacturing process.”
This initial survey of the PG 500 set the stage for the other processes that the NPDC worked to implement into the PG 500 manufacturing process.
“Jake turned out to be great for this project because he went in and he uncovered a lot of problems that were machine-related in the manufacturing process,” said Rajesh Krishnamurthy, Ph.D., OSU Applications Engineer.
Once it was discovered that the problems in the assembly process were directly related to issues in fabrication, Rowland went to work to solve the issues that were slowing production of the high-demand product.
“Cookshack was having a lot of issues with fabrication of the PG 500,” Rowland said. “During the fabrication process they take the big sheets of sheet metal that come in, cut them down, punch holes in them, and break the sheets into the parts before they go to assembly. Those parts were coming out inconsistently, in part due to the equipment, and in part due to the way the drawings were set up and the way the parts were designed.”
Rowland worked with design engineers at Cookshack to calculate the sheet metal stretch that takes place as the metal is bent during fabrication, which in turn allowed the parts created during fabrication to be more consistent.
“Whenever you bend sheet metal, it stretches from the force required to bend it,” Rowland said. “So, the sheet is going to get a little longer than it was before. If you want the sheet to be a very precise part after it is bent, you have to account for the stretch before you cut the part out and bend it.”
Rowland said to account for the sheet metal stretch, he calculated the amount each piece of metal stretched during the fabrication process and calibrated the design software used during production of the PG 500.
“Basically, I made an Excel Spreadsheet where if you take a test part that you know the flat length of, put a bend in it and measure the flanges after you bend it, you end up getting a constant,” Rowland said. “This constant is a number between zero and one that you input into the software program, in this case Auto Desk Inventor, and it accounts for the stretch for you.”
Rowland said the software calibration helped with consistency and allowed the team to design for better accuracy because there was less variance in material stretch from one piece to another.
Once the sheet metal stretch was accounted for, Rowland was able to revise the 3-D models of the PG 500 with help from NPDC Design Engineer Heather Lewis in order to more accurately match the grill that was output in production.
“My main role was to assist Jake in managing his tasks and resources to make sure that he met the objectives set forth at the beginning of summer. He worked diligently to deliver to the client the body of work that was promised and I believe his efforts have made a difference at Cookshack,” Lewis said.
From the revised 3-D models, Rowland was able to create production documentation for the entire assembly process.
“Two big problems are that they have separate engineering departments, and two separate software programs in use, and two separate drawings for the product,” Krishnamurthy said. “So, I think with Jake doing the PG 500 we showed them a template of how you just do one design, and through one simple click you change the design all the way through.”
Krishnamurthy said creating one set of design documentation for the product helped with consistency and helped to eliminate errors in the assembly process that were caused by confusion.
“Adding a full set of documents for the entire model helps standardize the production process,” Rowland said. “Before, if a new worker started or someone transferred from another model, they would just follow someone around and watch them do it for a couple days until they knew everything. Now they have documentation to assist in the training process.”
Adding the documentation helps ensure the entire assembly and fabrication processes are working efficiently and correctly, Rowland said.
Krishnamurthy said the changes made to the PG 500 production process can help the company improve manufacturing processes for other products as well.
According to the project impact report, Cookshack invested $40,000 for new equipment and software needed to implement the changes Rowland and Krishnamurthy suggested. However, these changes created three new positions at Cookshack, and for the first year of product, the projected sales for the PG 500 are an estimated $500,000.
Krishnamurthy added that the changes will also allow Cookshack to speed production of the popular PG 500, providing customers with the tool they need to get good barbeque.
“It was really exciting to me to see that something we did is actually helping them in a tangible way,” Rowland said.