Getting the Most Out of Peripherals
Peripherals — equipment that is integrated into the robotic welding process to make it more effective — can significantly boost the return on investment you achieve from your welding robot. And incorporating and operating peripherals successfully doesn’t have to be difficult. To help, it is important to understand how your peripherals are intended to function and employ some best practices for using them.
All robotic welding systems require some form of collision detection to prevent damage to both the robotic MIG gun and the robot arm in the event of an impact. Impacts can occur when the robotic MIG gun collides with an incorrectly positioned work piece or out-of-position tooling, or when the gun strikes an item that has inadvertently been left in the welding cell.
Some robotic systems incorporate robot collision detection software. Systems that do not have built-in collision detection, however, should always be paired with a clutch — an electronic component that attaches to the robotic MIG gun to protect it and the robot from heavy damage in the event of a collision. In some cases, you may choose to add a clutch to a system that utilizes collision software as backup protection for the robot.
Always make sure the clutch works with the weight of the load created by the robotic MIG gun and front-end consumables. If the gun is not properly supported and the robot moves rapidly to another spot on the other side of the part, the extra weight can move the clutch out of its optimal position.
If a clutch gets triggered from a collision, reset it by pulling it towards you and letting it snap back into position. After, be sure to check your tool center point (TCP) to ensure the robotic MIG gun is properly aligned for precise welding of the joint. If it is off center, validate that the clutch is in its home position.
If you have robotic welding applications that require consistent welding wire stick-out — the distance the wire extends from the end of the contact tip — a wire cutter is a recommended peripheral. As the name implies, a wire cutter cuts the welding wire to a specified length or stick-out and also removes any balling at the end of the wire.
Most wire cutters can cut a range of different types of welding wire, including stainless steel, flux-cored and metal-cored, usually up to 1/16-inch diameter. They can often be mounted on a nozzle station or used remotely as needed.
In conjunction with a wire brake, the wire cutter can ensure that the stick-out remains consistent for robots with touch sensing capabilities that help locate the joint.
Neck inspection fixtures
Another key peripheral is a neck inspection fixture, which tests the tolerance of a robotic MIG gun’s neck to the TCP so you can re-adjust it after an impact or after bending due to routine welding.
The advantage of adding a neck inspection fixture to a robotic weld cell is twofold. One, it ensures the neck meets the specifications to which the robotic welding system has been programmed and, once the tolerance has been determined, you can simply adjust the neck accordingly. This can prevent costly rework due to missed weld joints and can also prevent downtime required to reprogram a robot to meet welding specifications with an existing bent neck. Second, a neck inspection fixture can save you time, money and confusion when exchanging necks from one robotic MIG gun to another. Having this ability is especially advantageous if you maintain a large number of welding robots. You can simply remove a bent neck and change it with a spare that has already been inspected and adjusted, and put the robot back in service immediately.
Nozzle cleaning stations and sprayers
One of the most important peripherals you should consider for your robotic welding system is a nozzle cleaning station or reamer. A nozzle cleaning station removes spatter from the robotic MIG gun nozzle and clears away the debris that accumulates in the diffuser during the welding process. This helps lengthen the life of the robotic gun consumables, as well as the gun itself. A clean nozzle also reduces problems that could lead to rework and helps the robot create better quality welds.
During installation, be sure your reamer is on a sturdy base or otherwise securely fastened and not moving around during the reaming cycle. Ideally, the nozzle cleaning station should be placed in close proximity to the welding robot so it is easily accessible when cleaning is necessary. You should program the reaming process to run in between cycles — either during part loading or tooling transfer — so it does not add to the overall cycle time per part.
Always keep the covers on your reamer. The electronics within a reamer can be easily ruined by moisture from the atmosphere. Also, remember to use clean, filtered and lubricated air in your reamer. If “dirty” air goes into the reamer, it will clog up the valves. If you don’t have a lubricator installed on the reamer, use an alternative method to lubricate the air that goes through the motor.
It is important that your reamer matches the diameter of the nozzle and that the blade does not hit the diffuser or nozzle when it goes through a ream cycle. Be sure you are using the right blade for the nozzle you have and that your nozzle is set at the correct depth within the jaws of the reamer.
A reamer can be used by itself or in conjunction with a sprayer that applies an anti-spatter compound to protect the nozzle, diffuser and work piece from spatter. Make sure the nozzle is the correct height away from the spray block and that the duration of the spray is about a half a second. Too much anti-spatter compound can ruin the insulator on your nozzle, and can lead to unnecessary costs for replacement. The compound may also build up on the nozzle, the robot and the parts being welded, resulting in additional cleanup.
Frequently check that the sprayer and sprayer head is free of debris; if spatter gets inside the sprayer head, it will cause the spray plume to be distorted, which will create inconsistent coverage.
If you are using a multi-feed anti-spatter system, be sure you have a good quality hose, such as a urethane hose, and that it is protected from any spatter that may hit it and create a hole. Also, securely fasten the hose with clamps at every connection to prevent leaks.
You may consider using a spray containment unit to capture excess anti-spatter compound. If so, weekly inspections are recommended; remove any spatter or debris that may have fallen to the bottom. Failing to do so can prevent the unit from draining, which will cause the containment unit to overflow and create a mess.
No peripheral decision
The decision to invest in robotic welding equipment is significant. It requires time, knowledge and a trusted relationship with a robotic welding equipment manufacturer to find the right system. The same holds true for peripherals.
Although these devices do add to the initial cost of automating, they can lead to measurable cost savings and profits in the long run. But remember, the goal in robotic welding is repeatability and increased productivity, and any additional equipment that can help achieve these results may be worth your investment.