FDM Article

Taken from the January 2002 issue of FDM.

Nesting cabinet doors

in a BIG way

Nesting line cuts lead time for custom thermoformed doors at Australian company.

by Bruce Plantz
bplantz@chartcomm.com

Tesrol has grown to be one of the largest cabinet door producers in Australia by offering two things — quality and service. While maintaining quality has never been a problem, George Rizk, director, says service was becoming problematic as the company grew. The company was using a beam saw, two sliding table saws and four Heian CNC routers to machine MDF cores for its membrane pressing line and to be painted, but lead times kept going up.

“We were quoting three to four weeks lead time and running all that equipment 12 hours a day,” says Rizk. Meanwhile the company wanted to give itself a competitive edge with shorter lead times.

The answer was the FA system — a line of three Heian routers that is currently producing 900 to 1,000 door blanks a day on an eight-hour shift with two operators. Tesrol is now quoting four-day lead times for custom doors.

“When we first saw the price, we almost fell out of our chairs,” says Rizk, “but today we think it is the best investment we ever made. It has not just changed our ability to rout doors, it has changed the entire factory.”

Big project

Tesrol, which is located in a new 100,000-square-foot factory in a suburb of Sydney, started discussing the project with Heian over three years ago. At that time Rizk says “there were too many complications.” Meanwhile small door producers were offering five-day lead times and “pinching our clients, one by one. We said we had to do something big, something no one else could do.” That brought Rizk back to looking at nesting as a means to quickly produce door blanks for thermoforming or painting.

Two-part system

The system has two parts, which Rizk says are equally important. The first part is the machinery and the software to nest parts and control the machines. That was developed by Heian. The second part is the software to take orders and determine what should be machined each day. That part, called the Upper System, was developed in-house by Rizk and some developers.

“Mechanically this was all easy,” says Rizk. “The software is the key. A lot of people buying standalone machines for nesting don’t realize what they are in for. Our software and Heian’s software had to be perfectly integrated.” The result is that Tesrol can feed data into the Upper System and get product off the back of the line with almost no human intervention.

Rizk has a thorough understanding of both the software and mechanical side, which was a big factor in the project’s success. “It’s hard to find people who understand both sides,” says Rizk. “The machinery is really the simple part.”

The machinery

The core of the FA line are three Heian NC-231P two-spindle routers. Each router is equipped with automatic tool changers, with 25 tools per spindle per machine. This allows the tool to be changed on one spindle, while the second spindle is machining. This cuts changeover time between tools by a few seconds, but with an average of five tools required for each nest, that number adds up over the day. The dual spindles and tool changers also give some redundancy.

“If we have an accident or a spindle isn’t working, the machine can keep going with one spindle,” says Rizk. “Machines do break down. We also believe the machines will last longer by spreading the workload between two spindles.”

All three routers are fed from the rear by a panel transfer system. The line’s controller determines which panels should be fed into each machine, then sends the machine code for that panel to the proper router. The operator’s only task in machine loading is to keep the two raw material bays stocked. At present these bays are loaded with stacks of panels with a forklift. Rizk says the line was designed so the bays could be filled automatically from an automated warehouse, if Tesrol wants to expand in that direction.

Double check

When a panel is placed on the table the first thing that happens is its thickness is measured at six points. Rizk says there is variance in the thickness of the MDF Tesrol works with, so this stage is essential. If the variance is greater than 0.3mm, the sheet is rejected. If a piece of trash is stuck under the sheet, the variance will be large and machine will sense that and stop and sound an alarm so the operator can correct the problem.

The first thing that happens to the sheet is all the offcut material gets removed. If the offcut is over 170mm it stays on the table to be removed at the end of the line. Smaller pieces are turned to dust by the hogging tool. The hogging tool doesn’t cut clear through the sheet. It leaves 2mm of material, so the vacuum continues to hold the entire sheet, not just parts. “We do the hogging first because the spindle will travel a few times over the same path doing the hogging, face and edge,” says Rizk. “You can see some dust is left after the hogging pass, but the machine picks it up on the second and third pass.”

Then the second spindle starts on the face profile, switching back to the next spindle for the next tool. Some designs require as many as 12 tools. The program progresses to the edge profile. Even on the edge profile, the machine leaves 0.3 to 0.6mm of board in place, so parts are still held firmly. The last machining process is a straight edge tool that cleans up the last bit and moves 0.1mm into the spoil board.

Label everything

When machining is done, brushes come down and clean the parts so a vacuum table can lift them. The vacuum table then moves the parts to a labeling area and a bar code label is attached to each part. After labeling, the parts are moved to the offloading area.

Parts are offloaded manually, with the operator picking up each part and running it over a bar code scanner, similar to one in a grocery store. The monitor in front of the operator then tells him which batch to place the panel in by flashing a color.

“Automating this step would be easy,” says Rizk. “The system already knows where to place the parts. We just didn’t want to do everything at once.” The placement of the FA line was done with that further expansion in mind. The outfeed lines up with the automatic spray equipment in the next room for the membrane press, so nothing would have to be moved.

As for installation and startup, Rizk says there were almost no mechanical problems. “Since we’ve started, the line has been down for four or five hours, and that’s nothing.”

No startup pains

With the system in operation for over six months, Rizk is satisfied with its performance. “Before we were doing 800 to 900 doors a day with seven people. With this system we’ve done over 1,400 doors in 10 hours with two people,” says Rizk. “One operator loads the packs of material, checks machines, tooling and such. The other one offloads at the back.”

At the start of the project Heian was going to make the machine, purchase the nesting software, and get an outside company to make lifting equipment. In the end Heian did all the machinery and software themselves, and it’s all worked well together. “There has been no fingerpointing,” says Rizk. “If something doesn’t work, it’s our software or theirs. If it’s theirs, they have fixed it immediately. If it’s ours, it has taken a bit longer,” he says with a laugh.

“Mechanically we knew this wasn’t a problem,” says Rizk. “The lifting equipment is simple, the routers are straightforward. We saw the problem as being the software.”

Development time

Rizk says it took two years for Tesrol to develop its software, and Heian a year to develop the nesting software for the line. The two are now totally integrated. “I’d say 99 percent of the problems we’ve envisioned have been overcome.”

Both software projects were written in the same language — Visual Basic. Rizk describes Heian’s software as the machine interface, and Tesrol’s as a database containing all the patterns, tool setup, machine data and other parameters needed to machine the door blanks.

The order entry from Tesrol’s sales department is still done on the company’s existing computer system that does order entry and billing. This could later be integrated into the Upper System, but again, Rizk didn’t want to change everything at once. Those orders can be output in a simple comma delimited file and imported into the Upper System. “This can be done here, through e-mail, or in the future through the Internet,” says Rizk. The sales system gives us the quantities, sizes, profiles and colors we want to produce.”

Daily batch

The Upper System starts by batching all of the day’s orders by material. “When we’re batching all we care about is the thickness and material,” says Rizk.

Rizk points out those are the parameters Tesrol is working with today. If they wanted to batch by color, they could. The fewer parameters that batching is done by, the more efficient it is.

“To get the best nesting, you have to have five or six jobs,” says Rizk. “To get maximum performance from the machine you try to combine like profiles to minimize the tool changes.”

The batching program will give a graphical view of the panel and the yield. The production manager can either accept that, or try for a new combination.

“The production manager can sit here and take a day’s production and work with it until he is happy with all the nests and combinations,” says Rizk.

If a panel is accepted, the Upper System then collects all the needed data for that panel. That’s where the database comes into play. For each door profile in the system the Upper System has stored all of the needed machining information, including the tool paths. So the Upper System generates a file with all of that information and sends it to the FA line.

The controls

The FA line is basically controlled by a network of PCs housed in a small office next to the machine. Once the nesting is done, it is sent to PC2, the main control computer. It has the day’s schedule and the order required. The operator can adjust that schedule at PC2, if needed. PC2 tells the material handling what material to place in which machine and then sends the machine code for that nest to the machine’s controller. It also sends labeling information to PC3, which prints labels and controls the labeling device.

Rizk says they tried to build real world flexibility into the system. “If a customer needs an urgent job and we have six hours of work already scheduled on the machine, we can break into it and send down the urgent job.”

The office also houses a tool measuring system. All sharpened tools are measured, and those dimensions go directly into PC5, which controls the tooling component. PC5 knows the offsets and lengths of each tool, which machine that tool is on, and makes sure the machine’s controller has the right offsets for each tool.

With 50 tools on each machine, tooling for the line was a major investment itself. The system uses a combination of carbide and diamond tooling, with the majority of tooling provided by Stay-Sharp Ltd., which is also the Heian distributor for Australia. Brian Lynch of Stay-Sharp was involved in the development of the line from the beginning, so he understood the tooling component. “Tooling has been a lot better than we thought,” says Rizk. “We have an common edge profile that we changed for the first time last week, after three months.”

The laminating line

When parts come off the FA line they are loaded into carts. From there they either move to the thermoforming line or to painting. Today the thermoforming line consists of a Cefla robotic sprayer to apply adhesive followed by a Wemhoener membrane press. Parts move automatically from the sprayer to the membrane press. The press is equipped with three bays and Wemhoener’s automatic pin system. One bay is being loaded, one pressed, and one unloaded at the same time. “We’ve invested in the latest technology here and have the best of the best,” says Rizk.

The FA line was delivered to Tesrol in April of this year after two years of discussion and software development. Rizk says they had budgeted six months for installation, but it was completed and the line running in two months. That figure surprised everyone, but Rizk credits Heian’s engineering and software development team for “finding the problems in a conference room in Japan, not out here on the floor.”

The results

The result has been everything Rizk hoped for. “We took 10 days out of our process time. If you order a door on Monday, you will have it on Thursday. We eliminated four people sanding edges. We eliminated mistakes. With two people on the new line running 8 to 10 hours a day, we are feeding the laminating line running two shifts at 70 percent capacity.”

Using the panel saws and four routers with seven operators, the plant was producing 800 to 900 doors in 12 hours. Rizk says the FA line has produced over 1,400 doors in 10 hours.

As for the future, the software is in place to automate either end of the line. It can be fed from an automated warehouse and door blanks could be offloaded directly at the beginning of the laminating line, or put in storage. For now, those are just possibilities.

Find the limit

“You have to sit down and define what you want and how far you want to go,” says Rizk. The process could be automated from order entry, but he is not sure it’s cost effective, at least in the Australian market. “If I was a large door manufacturer in the U.S., I’d think about spending the money to make that happen,” says Rizk.

Rizk is so pleased with the system, he says he’s willing to share what he’s learned with anyone considering nesting on this scale. “If you were doing this for the U.S. or European market, there are some things you could do differently, but we’ve created a system that works, and works well.”