Modular design shrinks big machine problems

Ease of installation and simplified configuration changes outweigh initial design costs.

By Hank Hogan, contributing editor

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Going modular in its machine design was a matter of survival for Matrix Packaging, says Marc Willden, vice president and general manager. The Saukville, Wisconsin-based company designs and makes vertical form-fill-seal machines, the type of systems that produce potato chip bags with a sealed top and bottom and chips inside.

The machines typically weigh out, dispense, and then package product. Matrix Packaging also may provide printers, metal detectors and other peripheral equipment needed to interface with the rest of a food production line. Shortly after the company started more than 20 years ago, it was clear that the machines had to be customized, a challenge for even a large, established enterprise and a near impossibility for a startup.

“You simply don’t have the time or the money to design a brand-new machine from scratch. We tried it. It doesn’t work very well,” Willden says.

In contrast, a modular approach enabled the company to deliver customized solutions in a timely manner without bankrupting the OEM or its customers. Modular machines can save wiring and installation costs, as compared to a completely custom design. They also add flexibility and allow a greater variety of product to be produced in a smaller footprint compared to a one-of-a-kind approach.

However, pulling off a successful modular machine design does demand more planning upfront, and the result can be more costly for the first machine. After that, the savings can pile up. A look at several cases illustrates these points and indicates what’s needed for success.

When the chips were down

Consider Matrix Packaging’s experience. When it ran into problems at the beginning with a custom design, out of necessity the company totally redesigned the packaging machine it had at the time, putting it on a tubular frame that had the space needed to add different assemblies as required. The functionality changed little, but that was the beginning of a modular machine approach that Matrix Packaging follows to this day.

Over the years, the company has developed a number of options, such as assemblies that tuck the sides of a bag in before it’s sealed or load shelves to support very large bags. However, the options cannot be mixed and matched freely.

Also read: Modular Machine Building Succeeds in Sections

“It’s not possible to do physically,” says Mike P. Krummey, senior controls engineer. “So, as a result of that, the drawing standards that I have require maintenance. Any time that we build something new, I have to roll that into the standard.”

Krummey also maintains the software standards. The company uses PackML, which provides operating mode management and communication structures. This and a modular approach to software reduce engineering and integration costs, increase productivity and improve diagnostics.

One of the latest examples of this modular machine approach is the company’s Morpheus model (Figure 1), which was unveiled at the Pack Expo International trade show in Chicago in November 2014. The machine can flexibly fill up to 200 bags a minute and features continuous motion requiring the mechanical jaws that seal the bags to be precisely synchronized. The control system and servo motors are supplied by Beckhoff Automation.

Bob Trask, senior system architect at Beckhoff Automation, notes that the PackML standard started with the packaging industry and is now finding applications elsewhere. Another standard that makes it easier to produce highly connected modular machinery is OPC UA, which enables components to provide secure information to higher-level systems. This can include important metadata, or data about the data. For example, if a temperature reading is being produced, it helps to know if the data is supplied in Fahrenheit or Celsius.

As for the software side of modular machine design, object-oriented programming is a possible solution, but Trask cautions that this does mean making some changes in how software is created. Instead of a single block of code that runs from beginning to end, an object-oriented approach subdivides the task into smaller and reusable chunks.

When properly designed, this makes the software easier to maintain or alter. “It’s much less of an issue to add something or change something. The programmer doesn’t have to worry about negatively affecting other objects,” Trask says.

It does require, though, paying greater attention to source and version control, along with implementing systems to ensure both. Suppose that five people instead of one are working on a piece of software. It is important to make sure that they aren’t stepping on one another’s efforts. The use of software with built-in source code control or other means can eliminate wasted effort.

Savings by going modular

Another example of a modular design approach comes from machine maker OCME, a Parma, Italy-based manufacturer of packaging systems. These may, for example, label, pack and wrap beverage bottles so that they can be shipped (Figure 2). When it was designing a new system, OCME wanted to go modular, with distributed I/O and motion control.

The starting point was a centralized control cabinet and 33 motors. Cramming everything into a cabinet produced heat, which had to be dissipated by cooling modules that added to the cost and complexity of the system. There were more than 650 m of cabling, requiring 33 hours to wire. Installing the motors and other components took 20 additional hours.

In going to a modular design, the OEM sought to decentralize the architecture while reducing the time to wire and install everything. To do this, OCME wanted a machine in which everything could hang off a single network cable. That would make adding something like a conveyor as simple as plugging in a cable.

That goal of modularity placed certain requirements on the components. For instance, Antonio Mosca, OCME electrical department manager, says the company was “looking for a way to combine the motor and the servo drive into a single compact unit.”

When done with its modular design, OCME realized some substantial benefits. These included a 55% reduction in cable lengths and a similarly sized decrease in installation time. As a result, the overall cost of the machine was 10% less.

The combination motor and servo drive that OCME used was supplied by B&R Industrial Automation. They are IP65-rated and so can be machine mounted, with a single cable providing communication and power. They also support IP67 I/O blocks, so that sensors and other input/output elements can connect to the drive instead of having to run back to a controller. Thus, there can be one cable instead of many. Along with an automatic configuration capability, this helps enable modularization, says Derrick Stacey, solutions engineer with B&R.

A modular approach requires a shift in thinking, he adds. Solutions must be broken down into the smallest pieces possible, with the idea being that these will be common to different applications, and they will then be snapped together to produce the total, final solution. This means that the old approach of finishing a mechanical design and then throwing it over to the electrical team will not work. Instead, the interactions between the mechanical and electrical aspects and how everything will function together have to be established beforehand. Similarly, how to break up software into the appropriate modular chunks has to be settled.

This change in thinking extends to the design targets of the machine. It must be laid out in such a way that it allows for every conceivable module, a process that demands considerable upfront investment of engineering resources. It really epitomizes the approach of measuring twice and cutting once. “In many cases, it’s measure 10 times and cut once,” Stacey says.

Quick connection

When making a production line changeover, designing a modular machine to handle the task can prove beneficial. A case in point comes from RedViking. The Plymouth, Michigan-based integrator designs, builds and implements manufacturing and test solutions for the aerospace, off-highway, military and automotive industries. The company uses modular designs extensively for its gages, leak testers and powertrain test systems (Figure 3).

“When applied correctly, customers love it for its lower acquisition cost and reduced floor space,” says Mark Sobkow, vice president of manufacturing systems.

He points to automotive exhaust gages as an example of modularization. RedViking’s customers have to change tooling every model year. Previously, this meant creating an entirely new set of gages on dedicated machines. This was expensive and presented a logistics challenge, since last year’s machine could not be used for this year’s models.

With a modular approach, there is a docking station with fixtures swapped in and out as needed. The docking station has a PLC, light screens and other safety systems, pressure decay or mass flow instrumentation for testing, welding devices, control systems and other assembly devices such as strap guns or nut runners (Figure 4). So, if a line is running 10 models or parts, there could be one machine and 10 tooling fixtures instead of 10 machines.

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