Martin Control Systems, Inc.

Norse Dairy Systems, a division of Interbake Foods, is the top manufacturer of sugar cones in the world. From its headquarters in Columbus, Ohio, it operates facilities throughout North America that produce the baked wafers, cup treats and push-up tubes for our favorite frozen treats. But management realized it couldn’t keep its place at the front of the freezer without improving its efficiency.

Norse Dairy Systems, Inc., (NDS) has remained a top manufacturer in its industry by continually improving its products and internal processes. Four years ago, management committed itself to improving its processes and focused on the production of paper cone sleeves, which hold the wafer cone of a refreshing ice-cream confection. The machines that roll back the rim on the sleeves suffered from as much as 13% downtime and tens of thousands of dollars in wasted scrap paper.

The original rolled rim machine was chain-driven with glue applications, blunter, mandrel blow-off and vacuum, and rimming functions timed with cams. The cams, which are disks or cylinders varying in shape, travel in a rotary motion pushing against an actuator to achieve a linear motion. To adjust the timing for these functions, operators had to stop production and use hand tools to advance or retard the cam timing, then restart the machine to test the changes. This process would sometimes be necessary multiple times, further increasing machine downtime and eating into production capacity.

Making Adjustments on the Fly

NDS contacted Martin Control Systems, Inc. (MartinCSI) of Dublin, Ohio, in search of a solution. After conducting a system analysis, MartinCSI presented the idea to re-engineer the drive system on the rolled rim machine and incorporate a Programmable Logic Controller (PLC). This solution would allow operators to make adjustments electronically on the fly, eliminating the need to stop the machine, and provide a method of monitoring machine performance.

The system would be controlled by an Allen Bradley CompactLogix PLC and use an Allen Bradley PanelView Plus 1500 as the touch screen operator interface. An Allen Bradley PowerFlex 70 drive would be used for main drive speed control. An EMP Model 200 Single Motor Registration system would be reused to control paper registration into the cutting knives.

As part of the project, MartinCSI subcontracted with a local machine builder and industrial painting company to clean, rebuild and paint each machine prior to the installation of the new control system. As part of the re-engineering, all chains were replaced with timing belts during the rebuild for better control and timing accuracy.

For real-time monitor of the machine’s timing, a resolver was mounted on the main driven shaft and connected to an Advanced Micro Controls, Inc., (AMCI) resolver input module mounted in the CompactLogix rack. MartinCSI replaced the mechanical cams with an electronic timing schedule based on resolver position for three glue application points, the blunter stroke, cone blow-off and vacuum control, and the rimming operation. Machine operators now adjust the start and stop of machine functions without taking the machine out of production because the tedious cam adjustments have been eliminated. When adjustments are needed, the operator makes them on the touch screen while the machine is running.

The new control system provides runtime details about machine performance such as sleeve count, production speed (cones per minute), percentage of the maximum speed the machine is running, roll diameter (inches), and gate plug location. The main drive motor status and the rimming motor status are also displayed on the touch screen.

For quick startup after maintenance operations, MartinCSI implemented a resolver calibration function that uses a button on the HMI to re-time the resolver to the machine’s zero position.

Using the touch screen, operators can also change main motor speed, which is controlled by the PowerFlex 70. The knives, which are driven through the timing belts in a 1:1 relationship, run at the same speed as the rest of the machine, as do the resolver counts. When the machine speed is changed, it is no longer necessary to re-time the functions that are timed to the resolver as built-in compensation is provided for higher drive speeds.

Brake tension on the paper unroll is now adjusted electronically in real time while running, using an I-P transducer and an pneumatic disk brake. An ultra-sonic sensor is used to monitor the diminishing diameter of the paper roll, and as the diameter of the roll decrease, and thus the weight, brake tension is slowly reduced to maintain steady paper tension. The operator can establish diameter and tension ratios through the touch screen and can make adjustments while the machine is running.

Maintenance features, such as the ability to jog the machine forward using an operator plug for safety, were included in the new control system. The program monitors the location of the operator plug and when connected into the operator’s station, the machine has full capabilities. When the operator plug is removed and inserted into the remote push button station, the emergency stop and jog forward are the only available functions and all jog functions from the operator’s station are locked out.

To improve overall quality, a servo controlled paper positioning function replaced a manual screw and wheel system. An edge sensor now tracks the edge of the paper in relation to the rollers and signals for an adjustment of the paper roll to keep it centered in the knives.

In 2006, after the re-engineering, rebuild, installation and training, the total downtime of the rim roll machine was 5.15%. In 2004, 2005 and 2006, the downtime percentages are based on mechanical issues only and do not take into account machine starvation issues. In 2007, downtime due to lack of raw material (glue, paper, etc.) was added into the statistic, hence the slight rise from the previous year.

Minimizing Scrap Paper Waste

As the project progressed, the internal quality team at Norse Dairy Systems determined that the scrap paper levels of the rim roll machine were becoming the leading drain on profits. The rim roll machine uses large rolls of paper for the cone sleeves, and operators would simply watch the depletion of the rolls and stop the machine when they appeared to be close to their end. Rolls were scrapped with a diameter up to three inches of paper thickness remaining, producing total profit losses of over $40,000 a year. Operators cited the difficulty and amount of downtime necessary to re-thread the paper through the machine.

MartinCSI developed two solutions, focusing on the paper left on a roll at the end of its run, and a practice known as manually “holding blanks” during mandrel cleaning.

To ensure all paper was used, a sensor was installed to monitor the presence of paper coming off the roll and into the machine. Now, when the sensor looses the presence of paper, the machine is stopped and an alarm notifies the operator that the paper roll needs changed. This simple sensor completely eliminated the end of roll scrap, saving NDS 100% of the dollars lost.

Scrap due to manually held blanks occurs when glue on the mandrel, which sometimes “squeezes out” from the paper cones during production, is cleaned. This happens when operators catch the blanks of cut paper before they enter the mandrel so that excess glue can be scraped off. The machine would still be running at full speed during this operation. Once complete, the manually held blanks would be thrown away, resulting more than $35,500 a year in losses.

MartinCSI developed a control function to slow the machine when it is necessary to scrape the mandrel of glue. Blanks are still manually held by the operator, but due to the reduced speed of the machine, Norse dairy Systems realized more than over $28,000 a year in savings. This dropped the total scrap from manually held blanks to a little over $7,000 a year. Projected scrap totals for the current year are lower yet at $3,600.

Year Downtime % change from before install 2004 13.27% ---- 2005 10.23% - 3.23% 2006 5.15% - 8.12% 2007 6.72% - 6.55%   Year % of standard met Difference from previous year 2004 91.92% --- 2005 99.09% +7.17% 2006 119.8% +20.71%

During the scrap savings analysis, it was also found that the paper tended to get jammed coming into the mandrel without operator knowledge. The operator runs two machines at a time, back to back, and jams were occurring on the unmanned machine and not tended to immediately, adding to total scrap costs. MartinCSI observed this and added a function within the logic to use the cone counter to alert the operators of the jam. When the machine is running and jam detection is selected, if a cone is not counted for a specified amount of time, the machine slows down and now alerts the operator. After the operator clears the jam, with a touch of a button the machine can be up and running at production speed in a minimal amount of time.

In 2004, the total scrap for the rolled rim work center was 15.63%. By 2006, the total scrap from the work center was only 8.16% (See table).

Like any other manufacturer, NDS has production standards to meet. During the implementation year and those following, NDS consistently increased their percentage of standard production (See Table).

The project performed by MartinCSI enabled NDS to generate an overwhelming rise in production, due to decreased downtime and a drop in labor costs. One operator can now run twice as many machines. In 2007, NDS management was forced to raise production standards for the rim roll machines. Even after the heightened production requirements, statistics show that the rim roll machines continue to exceed expectations.