Operating a wire or cable production line can be complex and may include drawing, annealing, stranding, jacketing, spooling, and even packaging for final shipment. Despite the best practices and intentions, many things can go wrong.
Wire and cable manufacturing encompasses many concurrent processes. The slightest problem, which sometimes goes undetected, can result in significant waste and rework. If your line goes down, troubleshooting and downtime can be costly. If your hardware is outdated and lacks advanced automation too, your production line may require much manual intervention. Any new operator must adjust to archaic displays that are not so user friendly.
Including advanced automation hardware and software, as well as implementing smart maintenance management, is best practice that can pay dividends. New automation control hardware and its programming are essential to not only meeting quality standards, but also for staying relevant in a globally competitive race for quality, cost, and speed of product delivery.
HAVE YOU EXPERIENCED THIS?
Your QC department rejects the spools coming out of the drawing machine for being too hard – a result of improper inline annealing. Your stripe extruder is creating a wider than desired color band and/or the jacketing is necking. Or maybe you’re just plain tired of excessive downtime and buying replacement parts on eBay. With so many complex processes inside of a modern Wire and Cable plant, there are scores of things that can go wrong. Here are a few more of the issues that EDC commonly finds hampering their customers’ success:
- Line runs too slow or will not hold speed regulation
- Excessive wire breaks
- Annealer voltage regulation is inconsistent
- Only one spool of dual spooler is operational
- Lay turns per inch are too high or too low
- Take-up tension is too tight or too slack
- Line or tape breaks
- Excessive set-up time due to mechanical intervention required
- Closer malfunctions or is finicky due to old, dirty hydraulic components
JACKETING & CONTINUOUS VULCANIZATION (CV)
- Hot or cold spots in extruder barrels or unable to maintain proper temperature in barrels or dies
- Improper colorant or compounding mixes/weighs
- Concentricity, ovality or necking
- Unable to maintain proper wire tension throughout line
- Unable to maintain proper ratio between extruders
- Capstan following issues, slippage, speed range shortfall
- Poor Accumulator transition at reel change
- Pay-off and Take-up speed regulation
- Take-up Traverse pitch or turn-point irregularities
- Take-up Traverse jog speed too slow
- Water level in steam tube inconsistent (CV)
- Nitrogen blow-outs (CV)
- Footage count is too long or too short
- Finished product touches the floor or scuffs
- Changing spool sizes takes too long
- Shrink wrapping, bagging or labeling issues
GENERAL CONTROLS /PERSONNEL ISSUES
- Obsolete drives and/or PLCs
- DC motors unavailable or too expensive to refurbish
- Difficult to train new operators on older equipment without a rich graphics display and dashboard.
- Analog controls should be replaced with digital to eliminate variations due to temperature, humidity or electrical noise
- Shift-to-shift set-up inconsistencies
- When a recipe changes, new parameters such as temperature and speed must be manually input, instead of programming a PLC to orchestrate such changes.
- Manual intervention of older, legacy components risks set-up issues
- Excessive scrap and/or downtime
- Mechanically, your line has inadequate feedback loops for things like temperature, speed, and cooling, causing an otherwise well-performing process line to not perform well.
There are many ways to approach eliminating one or more of the above Wire and Cable pain points. Narrow down your process lines and determine which areas need the most attention first. Gather information from all sources to determine where to focus first and where to spend the most effort. Refer to hard facts, as well as anecdotal data from technicians and operators to do this most effectively.
Here are some ideas depending on the nature of the issue, the time available to address them and, of course, your budget.
Attack a specific component or two to relieve the pressure.
Stuff gets old. Components become incompatible. Long term exposure to the elements leads to material degradation. Dirt and grime cause all kinds of problems. Replacing just one item can make a world of difference.
Here are a few examples:
- Check the wiring first! – EDC’s mantra and go-to before changing anything. Depending on the complexity of the controls (or the rat’s nest in your enclosure), a day of troubleshooting with a controls expert will pay for itself
- Replace the Pay-Off I/P (current-to-pressure regulator) – it could be dirty or clogged or the analog circuitry is failing, preventing proper pressure regulation to the brakes, which is directly related to tension control.
- Don’t forget to change the brake pads – just like for your car, these pads are only rated for so many miles and require routine maintenance
- Recalibrate the load cells – poor feedback leads to poor control
- Clear the air – make sure your compressed air source is clean, moisture-free and properly oiled. Stiction in pneumatic cylinders (think Dancers) is your enemy
- Motor checks Part I – start by megging the motors to check for shorts or insulation breakdown. If you have DC motors, check/change the brushes. And while you’re down, make sure all the mechanical elements, belts and pulleys are tight. We have had plenty of drive service calls that turned out to be a loose coupling.
- Motor checks Part II – A previous maintenance team may have swapped a failed motor for a lower horsepower, getting away with it because the frame size is similar enough. Now your line speed is compromised since you do not have enough torque. Likewise, if you want to increase your line speed you’ll likely have to start by increasing motor horsepower and perhaps mechanical component sizes. Remember:
HP = LINE SPEED (feet/min.) x TENSION (lbs.)
For motorized Pay-Offs and Take-Ups, multiply the resulting HP by the build-up ratio.
- Implement maintenance rigor and document it all, maintaining careful historical maintenance files. A disciplined planned maintenance management program is a smart defense to fend off problems. Take motors for example: have a scheduled program to megger the motors regularly (also known as an insulation test) to check for shorts, grounds, or insulation breakdown, which can signal a need to rewind or replace a motor before it fails unexpectedly during production. Take regular infrared camera shots to find loose connections and hotspots that can lead to bigger problems. If you have DC motors, check/change the brushes. During shutdowns, make sure all the mechanical elements, belts and pulleys are tight. Many drive service calls related to drives turn out to be a loose coupling.
FOCUS ON A MACHINE SECTION
Annealers, Spoolers, Taping heads, Capstans, Accumulators – these are of course some of the sections of a wire and cable line that need coordinated components to function properly. You may not need to retrofit the whole line or may not have the time and money to do so. Perhaps you can focus on a single problem area:
- As an example, many cable lines utilize two Pay-Offs and two Take-Ups per line, each with up to two motors if traversing is utilized. Replacing the motors and drives will breathe new life into that critical section. You may want to take it a step further and convert your old, hard-to-find DC motor to AC. Tying together the DC buses of a Pay-Off and Take-Up will save energy and may eliminate the need for a regenerative drive.
- Maybe your PLC is a generation or two old. Instead of yanking out the entire rack, add a stand-alone CPU and use the rack and existing wiring as remote I/O. The PLC program can be converted and tested offline prior to installation saving hours or even days. This can also provide a foundation for modern-day machine communications (think IIOT) and manufacturing intelligence, helping you to capture and analyze key performance indicators (KPIs).
- Similarly, you may have what’s called “islands of automation,” where a line contains two or more independently functioning PLC’s or dedicated controllers. Again, utilizing the remote I/O strategy the PLC or controller can be replaced with I/O that can communicate with the main PLC. The code is moved to the single, main PLC CPU which has faster scan times, modern control capabilities and improved overall performance.
- Temperature control improvements: move them to the PLC. Tired of having to program each individual temperature controller for each zone, sometimes ten or more! Not to mention the fact that you may have three or more brands as failed controllers were replaced by what was available or in stock at the time. With the advent of faster, more robust PLC processors multiple PID loops can be programmed to handle all of the zones, including negative feedback (cooling) for each extruder on the line. A nice windfall is the ability to move all of the set-up to a single touch screen and utilize a recipe for each product. Your process engineer will love you! (If you’re the process engineer, you’ve earned some well-deserved bragging rights)
- Laser Sensors – These expensive components are critical to providing feedback to the extruder(s) to control line speed, diameter, ovality and other important process parameters. Often they are what stands between a quality product and scrap. Like any other controls component, laser sensors become obsolete, can fail or perform intermittently. While repair or replacement may be the best strategy, check to see if the manufacturer has an upgrade path. Better yet, upgrading from analog or serial feedback to a digital protocol such as Ethernet I/P can provide more reliable feedback and performance. Of course, this may necessitate adding a communications module to your PLC and some programming. The effort will be well worth the investment. Again, a qualified systems integrator can help make this happen while you’re busy taking care of other parts of the plant.
- Has something changed in your process? Are you running faster or maybe running larger gauge wire or a thinker jacketing? Maybe an operator cranked up the speed, which is causing a machine section to under-perform. Again, by taking a sectional approach, you can likely isolate an issue and determine which inter-related components are causing the largest headaches.
FULL LINE RETROFIT
So now it’s time to bite the bullet. No more band aids, no partial fixes. You have budgeted the funds and are building up enough stock to cover you for the line being down during the turnover demo/installation window. Despite the fear that you may be feeling, an expert systems integration firm will help ensure you get another 20+ years from the newly installed controls. A full retrofit can encompass some or all of the fixes recently cited plus the following:
- Create PLC architecture that includes HMIs, remote I/O and drives all on the same communications network
- Eliminate outdated comms protocols or those with less bandwidth such as Device Net, Control Net, Modbus, Profibus, IO Link, etc.
- Install HMIs that replace rows of pushbuttons, dials, meters and operators, keeping the buttons you use most often. Add recipe capability, alarm screens and user-friendly graphics (see also the section on Temperature control improvements above.)
- Replace analog or obsolete drives with late model drives networked to the PLC. Utilize advanced PID function blocks in the PLC rather than the drives
- Improve the overall safety of the line, perhaps utilizing a failsafe PLC and/or adding cable operated switches and interlocks to replace unsafe microswitch devices; Replace existing E-stop buttons with illuminated versions that will tell the operator which button or zone has been depressed
- Replace load cells and amplifiers – ones that work all day, every day!
- Completely rewire the line to get rid of jumpers, splices and wires that no-one knows where they come from. At the same time add proper grounding and shielding, perhaps using VFD cabling.
- Replace OEM-designed motors/geartrains or electrical components with off-the-shelf counterparts from major automation controls manufacturers (ABB, Parker, Rockwell, Schneider, Siemens, Yaskawa, etc.)
- Consolidate disparate control panels into a new enclosure or enclosure group with proper electrical design, layout, labeling and no wires laying around in the bottom
- Resuscitate defunct machine sections and functionality
- Add an encrypted remote access device that makes it possible for the systems integrator or other vendors to troubleshoot your line from anywhere in the world. Have an overbearing IT ogre who won’t let you into the company network (who doesn’t) – use a cellular-enabled device or connect to your internet only when needed. One less service man’s plane ticket, hotel and meals will pay for it many times over!
Your Wire and Cable line keeps you up at night or away from home on the weekends. There are many relatively small steps you can take to take a bite out of the larger issue. And if need be or if it is just that time, you can retrofit the whole line without needing to install a more expensive, completely new line for a fraction of the cost and in less time.
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If you need further help with your Wire and Cable line, reach out to EDC today.