Roughly four sensing-related processes occur in a welding cell with regards to parts that are to be joined by MIG, TIG and resistance welding by specialized robotic /automated equipment:
Nesting…usually, inductive proximity sensors with special Weld Field Resistance properties and hopefully, heavy duty mechanical properties (coatings to resist weld debris accumulation, hardened faces to resist parts loading impact and well-guarded cabling) are used to validate the presence of properly seated or “nested” metal components to ensure perfectly assembled products for end customers.
Poke-Yoke Sensing (Feature Validation)…tabs, holes, flanges and other essential details are generally confirmed by photoelectric, inductive proximity or electromechanical sensing devices.
Pneumatic and Hydraulic cylinder clamping indication is vital for proper positioning before the welding occurs. Improper clamping before welding can lead to finished goods that are out of tolerance and ultimately leads to scrap, a costly item in an already profit-tight, volume dependent business.
Connectivity…all peripheral sensing devices mentioned above are ultimately wired back to the controls architecture of the welding apparatus, by means of junction boxes, passive MIB’s (multiport interface boxes) or bus networked systems. It is important to mention that all of these components and more (valve banks, manifolds, etc.) and must be protected to ensure optimum performance against the extremely hostile rigors of the weld process.
Magnetoresistive (MR), and Giant Magnetoresistive (GMR) sensing technologies provide some very positive attributes in welding cell environments in that they provide exceptionally accurate switching points, have form factors that adapt to all popular “C” slot, “T” slot, band mount, tie rod, trapezoid and cylindrical pneumatic cylinder body shapes regardless of manufacturer. One model family combines two separate sensing elements tied to a common connector, eliminating one wire back to the host control. One or two separate cylinders can be controlled from one set if only one sensor is required for position sensing.
Unlike reed switches that are very inexpensive (up front purchase price; these generally come from cylinder manufacturers attached to their products) but are prone to premature failure. Hall Effect switches are solid state, yet generally have their own set of weaknesses such as a tendency to drift over time and are generally not short circuit protected or reverse polarity protected, something to consider when a performance-oriented cylinder sensing device is desired. VERY GOOD MR and GMR cylinder position sensors are guaranteed for lifetime performance, something of significance as well when unparalleled performance is expected in high production welding operations.
But!!!!! Yes, there is indeed a caveat in that aluminum bodied cylinders (they must be aluminum in order for its piston-attached magnet must permit magnetic gauss to pass through the non-ferrous cylinder body in order to be detected by the sensor to recognize position) are prone to weld hostility as well. And connection wires on ALL of these devices are prone to welding hostilities such as weld spatter (especially MIG or Resistance welding), heat, over flex, cable cuts made by sharp metal components and impact from direct parts impact. Some inexpensive, effective, off-the-shelf protective silicone cable cover tubing, self-fusing Weld Repel Wrap and silicone sheet material cut to fit particular protective needs go far in protecting all of these components and guarantees positive sensor performance, machine up-time and significantly reduces nuisance maintenance issues.
Walk into any die shop in the US and nine out of ten times, we discover diffuse reflective sensors being used to detect a large part or a small part exiting a die. Many people have success using this methodology, but lubrication-covered tumbling parts can create challenges for diffuse-reflective photoelectric sensing devices for many reasons:
Tumbling parts with many “openings” on the part itself can cause a miss-detected component.
Overly-reflective parts can false triggering of the output.
Dark segments of the exiting part can cause light absorption. Remember, a diffuse sensors sensing distance is based on reflectivity. Black or dark targets tend to absorb light and not reflect light back to the receiver.
Die lube/misting can often fog over a photoelectric lens requiring maintenance or machine down time.
The solution: Super Long Range Inductive Sensors placed under chutes
Most metal forming personnel are very familiar with smaller versions of inductive proximity sensors in tubular sizes ranging from 3mm through 30mm in diameter and with square or “block style” inductive types (flat packs, “pancake types”, etc.) but it is surprising how many people are just now discovering “Super Long Range Inductive Proximity” types. Super Long Range Inductive Proximity Sensors have been used in metal detection applications for many years including Body-In-White Automotive applications, various segments of steel processing and manufacturing, the canning industry, and conveyance.
Benefits of Using A UHMW Chute + Super Long Range Inductive Proximity Sensor in Part Exit/Part-Out Applications:
It is stronger and quieter than parts flowing over a metal chute, readily available in standard and custom widths, lengths and thicknesses to fit the needs of large and small part stampers everywhere.
UHMW is reported to be 3X stronger than carbon steel.
UHMW is resistant to die lubes.
UHMW allows Super Long Range Inductive Proximity Sensors to be placed underneath and to be “tuned” to fit the exact zone dimension required to detect any part exiting the die (fixed ranges and tunable with a potentiometer). The sensing device is also always out of harm’s way.
Provides an option for part detection in exiting applications that eliminates potential problems experienced in certain metal forming applications where photoelectric sensing solutions aren’t performing optimally.
Not every Part Exit/Part-Out application is the same and not every die, stamping application, vintage of equipment, budget for sensing programs are the same. But it’s important to remember in the world of stamping, to try as consistently as possible to think application specificity when using sensors.That is, putting the right sensing system in the right place to get the job done and to have as many technical options available as possible to solve application needs in your own “real world” metal forming operation. We believe the UHMW + Super Long Range Inductive System is such an option.
Applications where sensor contact is unavoidable are some of the most challenging to solve. Metal forming processes involving over travel can also damage or even destroy a sensor causing failure and expensive unplanned downtime. Manufacturers often try to remedy this with in-house manufactured spring loaded out-feed mechanisms but those are expensive to make by experienced tool and die personnel who have more important things to do . Over the years, I’ve seen this as a pervasive problem in the stamping industry. Many of these issues can be solved with the use of a simple yet effective sensor actuator system known as a plunger probe.
Plunger probe solves a few key issues in Progressive stamping:
The flexible trigger/actuation point is fully adjustable to meet sensitive or less sensitive activation points, not possible with “fixed” systems with substantial “over travel” built into the design.
It is fully self-contained (minimizing any risk of sensor damage and resulting unplanned machine down time).
The device can be disassembled and rapidly cleaned, reassembled, and placed back in service in the event that die lube or other industrial fluids enter the M18 body that can potentially congeal during shut down periods.
During the recent economic downturn, businesses have lost scores of experienced, trained personnel who were very familiar with (among other things) monitoring the health of their DeviceNet System and who may have been responsible for keeping things “up and running”. Now that business is ramping back up, companies are running lean and we’re all doing “more with less” of everything (including people), the need for rapidly diagnosing issues on a DeviceNet system has increased. These reasons are exactly why the DeviceNet Analyzer was developed.
The analyzer is a collection of components used for analysis, monitoring and maintaining DeviceNet systems without having to call a third-party to conduct these procedures. The ROI is amazingly fast after technicians have been trained on the use of this powerful tool for checking DeviceNet and CAN bus installations:
Analyze and track down telegrams with poor signal quality. Check for causes of faults, like missing bus terminations (or too many bus terminations), faulty bus drivers, or trunk and drop lines that are too long.
Physical cable troubleshooting is accomplished on a “wire test” function that detects the location of cable breaks and short circuits. “Weak Spots” like incorrect cable types, lengths, and faulty plugs are also located.
Monitor…comparisons can be made at regular or continuous intervals via an online function. Gradual degradation of system quality can be seen and proactive preventative maintenance can in turn be enacted.
If you have DeviceNet “Heartburn”…there is an Antacid! For more information on the DeviceNet Analyzer, click here or watch the video below.
Plural of Giz-mo. A noun. Defined as a gadget, one whose name the speaker does not know. Customers call us and ask for this or that “gizmo” all the time! I think we should consider creating a product category simply called “GIZMOS”.
I like to call these things “Enablers” because these devices are very much helping hands that optimize the function of sensors. A sensor of any brand and manufacturer performs only as well as it’s mounted, matching the fixture to the demands of the application at hand. But how often does this happen in a price-driven world? They often end up in below-par mounting that fails with regularity, in both pristine environments as well as in hostile environments. Some examples:
Here’s one example below. These inductive proximity sensors in plastic brackets, showing an exposed coil on one, with corroded mounts on the sensor caused by being beaten to death during parts loading and heat.
With a few “Gizmos” like an application-specific quick change mount, some care in gapping the sensor and guarding the cable/connector system, it could look much different. Check out the examples below.
Photoelectric sensors can suffer the same fate. In this case, a plastic bodied photoelectric sensor, originally used to replace a fiber optic thru beam pair also suffered abuse. With a little extra beefy mounting, these photoelectric sensors can be expected to last a long time without failure.
Have you ever heard the phrase, “Nine pounds of stuff in a one pound bag?”, or otherwise known as the “Blivet Effect?”
I’ve recently experience this, actually four incidences in three different companies to be exact. It revolves the wrong shut height. When the recipe in a press doesn’t match die dimensions, or when the die dimensions are estimated, some bad things can happen.
In all of these companies, stamping presses of various tonnage ratings were run with a die that was over shut height dimension (the first hit caused a kaboom!). Dies were locked up so badly, that they had to be torched, cut, and/or mechanically coaxed out. In all cases, it took several days for this process to take place, causing lost production and significant down time (not to mention the financial loss and aggravation for a multitude of employees).
This post will show how to couple stamping die segments without a hard wire connection, AND prevent the potential gorilla-like effects of forklifts during die change! Have you ever experienced or heard about a forklift removing a stamping die with the giant Mil-Spec connector still attached (OOPS!!!!)? It certainly isn’t a pretty sight. Below is a typical Mil-spec connector, they aren’t cheap or easy to re-wire.
Or, have you ever tried to figure out a way to add sensors in very complex progressive die segments that will facilitate rapid die change? If so, I have an answer for you with a non-contact connector system. Take a peek at the picture below.
Answer: Because it has the extreme potential to save a lot of money. The general mentality these days, with regards to inductive proximity sensing, has been, “Lowest price wins the business”. Some manufacturers and industrial consumers alike have been accused of treating these devices as true commodities. Some salespeople have also caved in over the years with regards to price pressures in exchange for the big win. We’re all guilty to a degree, for leaving money on the table and hastening price degradation for this category of automation device over the years!
Maybe a little of this is justified. As electronic device manufacturing volume increases, prices for sub-components used to make these sensing devices decrease while manufacturing methodologies become more streamlined. The result is that cost comes out, prices drop and the game becomes more globally competitive. But with regards to application specific, hostile sensing applications, there must be a paradigm shift otherwise consumption can become gargantuan, both for material and for labor costs in the real world of factory automation. Using “generic” non-application-specific sensors in rotten environments, like welding for parts presence or Poke-Yoke applications, creates a problem. “Generic” sensors fail with regularity, change out becomes a massive maintenance issue, machine down time becomes costly and even bad parts can potentially be made (a really bad problem….audits and everything associated with shipping bad parts must obviously be avoided as much as possible).
An artificial lift is a device used in the oil and gas industry when there is insufficient pressure necessary to lift fluids from a oils well to the surface in already-drilled wells or in new wells, to increase the flow rate above what would flow out naturally. You can see what an artificial lift looks like in the picture to the right.
Hydraulic cylinders are used in the valve systems of artificial lift systems to move fluids in and out of the process. An explosion-proof transducer is the perfect choice for mounting inside the cylinders for valve control, as it is a Class 1, Division 1 Certified unit that can be used in these potentially explosive environments (pictured at bottom).
Picture this scenario. You, your spouse, or one of your kids happens to be riding one night in the middle of nowhere when a tire blows on the car. First, we can only hope that your loved one remembered the lesson they received on how to change a flat tire in a pinch (if we gave it to them in the first place), because on this particular night, there’s no cell coverage where they’re at, AAA isn’t going to get to them very quickly, there isn’t a can of Flat Fix in the trunk, and there isn’t much traffic on the road they’re traveling on for a good Samaritan to likely show up any time soon (the scenario is extreme, but not impossible). The jack kit sitting under the spare tire is going to seem pretty doggoned important, don’t you think?
We take a lot for granted these days and for those of us who have been involved in the world of factory automation for many years, getting to work with customers to help solve Error-Proofing challenges on the plant floor is like one big “Class Trip” every single day! It’s kind of like providing our customers with “toys for adults”. And it’s a real hoot. We get to see how stuff is made, get the opportunity to help manufacturers build better products through our Error-Proofing sensing technologies and learn over time which end products to buy and which ones to shy away from! We also quickly realize the extreme importance of the DETAIL! Like the components in the emergency jack kit! What if the main handle was missing when you or your relative went to jack up the car? What if there wasn’t any grease on the main lift shaft threads and the car couldn’t be raised? What if other parts were missing from the kit? Not a good scenario.