My first piece of advice is to get in touch with someone that is not limited to selling only one type of robot or only used or only new. Prices of new robots with welders (below $40 k) are very close to prices I hear people have paid for used packages so ask how much a new one is. Prices of excellent, large used robots could be a fraction of the price of a new one and perform the same if you intend to automate your welding process.
Secondly, remember you are buying a welding machine, not a robot. You are buying the arc. You might need more support in robotic arc welding than for the robot itself. Buy from someone that can weld. Ask the robot seller for free consulting on tool building, system design assistance, cycle time calculation, and cost of consumables (remember CO2 welding is an option for Japanese power supplies). It will help you calculate how much capital you need to invest, help you quote prices per part to your customers, or to weld prototypes for you.
Next, do not be afraid of electronic board failures on used equipment. MIG welding robots are very inexpensive in terms of cost of repair per year. Most of the costs come from service or from downtime usually caused by the welding process, plant personnel mishandling the arc welding parameters, failure to detect a faulty welding tip or wire liner, faulty torch, or wire feeding problems, bad batches of weld wire, oily parts or gas problems have caused and will cause considerably more downtime than the robot electronics or mechanics.
Fourth, train your personnel. The more training you have, the greater the chances you will have a successful robotic automation. Training courses can be very expensive. Try to negotiate free or extra training with the purchase of a robot. Welding development could take a long period of time. Aluminum or seam multi pass welding especially require welding expertise and robot knowledge. Try to assess how much support you will get from the robotic company. Finally, buy a system from somebody that has production floor experience. Ask questions such as:
- How many tip changes per shift?
- What is a tip changing procedure?
- Do you need a tool center point check and auto adjust or nozzle cleaners?
- What is the number one cause of production downtime in robotic systems?
- What safety measures are taken when accessing cell?
- Ask for details on fixture building.
Buying a Used Robot
Used robots could be purchased with warranty that could match the warranty of a new robot. Material handling robots could be purchased used in good condition, excellent condition, refurbished. Prices of used should be anywhere between 15% to 65% of the price of a new robot. If buying an arc welding robot see purchasing a power supply.
Buying a Power Supply
You have to be aware that welding power supplies have evolved a lot lately. The ones manufactured recently have drastically improved the arc. You may weld with reduced spatter, weld at higher speeds, or weld without changing the welding tip for days. There are power supplies that weld well using CO2, an inexpensive gas. Where applicable, buy gas in bulk. Used robots could perform most of the time as well as new. Newer robots have higher speeds which might be requested by particular applications such as press tending or material handling at high speeds if cycle time is not the most required criteria. Used robots could be used successfully as they have similar closed computing or interfacing capabilities as a new robot. A used robot purchased for MIG welding will perform as well as the welding power source is capable of welding. The robot is just a manipulator, arc welding software and robotic interfacing hardware gives the welding process more flexibility. The market offers welding robots that are factory integrated with the power supply. These robots are ready to weld when shipped from the factory (see buying a new robot). These robots will outperform in arc quality, weld speeds and uptime, the robots that need to be ‘married’ with the welding equipment. Buy a robotic system with warranty on every cell component if possible. New Age Robotics builds cells with warranty as well as selling the ready built Panasonic cells. New Age also offers service on:
- Robot, electrical, electronics, mechanical
- Welding power supply (Panasonic)
- Electrical controls
- Welding JIGS
- Auxiliary equipment such as nozzle cleaners
- We carry consumables
Buying a Robotic System
Make sure you enter into a contract with a company that can help you from concept, design, execution, training, service, and maintenance. Ask for a cycle time study, tool design ideas, graphic simulations, prototype welding, and welding start parameters.
Make sure tool design is executed to suit a robotic application. There are a lot of tool houses that claim that they can build or have built welding JIGS. Remember a welding JIG is not a forming die, welding JIGS need to allow adjustments in case the parts vary or welding process distorts the part. Suitable materials need to be utilized. Spatter resistant sensors, spatter resistant isolation should be used for electrical wires. Copper air conduits are preferable for the pneumatically actuated clamps. Most important, make sure the tool design does not interfere with the welding process. Inappropriate tool design can cause inappropriate torch angles or increased cycle times due to obstacles created by the tool designer. The robot needs to reach every weld with the torch at the right welding angle and avoiding robot axes singularity points.
Buying a New Arc Welding Robot
Choose a robotic company that specializes in arc welding. Sometimes well known robotic companies have very little expertise in arc welding. You do not want to end up with the gas/ wire distributor tool house building the JIGS or robot integrator as your arc welding specialist. They are often only knowledgeable in welding and robots. Robot speed is not the main concern, all robots are built very speedwise. New robots are all very fast. Flexibility is reduced singularity points. A robot that has no parallel arm is more flexible. Choose an arc welding integrated robot. These robots, properly handled, will outperform the robots that need to be integrated by a local company. The robot and power supply have software and communication capabilities not superior to those that require relay interfacing. You need a digitally interfaced robot mainly if you do high speed welding, high volume short welds, or tack welds.
The advantages of digitally interfaced MIG welding robots consists in: higher welding speeds, extremely reduced arc faults, next to zero welding tip replacement due to tip melting, shorter commissioning time due to much increased uptime. Most robotic companies sell robots that need to be married to a welding power supply. In spite of the fact that the robot comes with arc welding software, it communicates with the power supply via relays. More than likely you will get more arc faults therefore much more production downtime than with digitally integrated welding robots.
Cornel Cosma, President of NAR