Rarely is robotic welding seen as anything other than a no-brainer for high-volume manufacturing. The technology has been around since the 1980s, and the payback for high-volume operations can be measured in mere months; plus, you gain a range of secondary benefits. The challenge for local manufacturers has been making such investments work with challenging low-volume, high-mix operations.
This is the first in a series of robotic welding articles that will demonstrate the state-of-the-art technology and how advancements in usability, and Industry 4.0 concepts, offer many more opportunities for our local industry.
State of the Art Robotic Welding
Industry figures put welding applications at about 25-30% of all global robot sales, and this significant market drives targeted R&D by the major players. Technology in all manner, including capital outlay, capability, and ease of use, has dramatically improved since the early days of robotic welding.
The days of one robot being fixed to welding the number 4 engine bracket on the jeep wrangler disappeared decades ago.
Technology advancements have brought increased competition and lowered the cost of equipment. Incredibly intelligent modern welding power sources, robotic sensors, and vision systems now allow complex welding challenges to be automated with off-the-shelf equipment. These smart features have made robotic welding operations more robust and handle wider variability, allowing the systems to work longer and have fewer stoppages with minimal operator input.
Another avenue of this development race has been the simplification and de-experting of the use of robotic welding systems. Improvements in offline robotic programming and dedicated robotic welding software have simplified the necessary technology skills. These user-ability improvements are game changers for local businesses and can offer a massive 90%+ reduction in the cost of programming parts. Combining this increased part programming efficiency with the digital factory from Industry 4.0 allows high-mix, low-volume production.
Robotic Welding Opportunities for NZ Industry
The technology convergence opens many automation options for smaller niche operations in NZ and Australia. In local welding operations, this significantly reduces the two long-standing challenges of returning a payback on a robotic system.
- Improved programming tools reduce the long-standing problem of returning a payback when faced with programming a small volume of parts.
- Industry 4 connected systems allow the easier, possibly fully automated, part changeover for high-mix operations.
This provides the robotic welding investment opportunity for SMEs to increase their competitiveness and manageable ways of scaling capacity. These improved user-ability factors, and others on the horizon, are critical factors for many NZ manufacturers and will be discussed in later articles.
Robotic Welding Benefits
Weighing up the case for robotic welding requires gathering a comprehensive picture of your operation and exploring potential opportunities for indirect gains. This is a simple equation for large-scale manufacturing operations with double or triple shifts. In these operations, a robot welding system can produce the production equivalent of 7-10 people. Combine that output with the starting price of a quality robot cell in the range of 120K NZD, and it makes sense to measure the payback in mere weeks. Unfortunately, such local applications are rare and therefore require careful analysis of your current and potential operation.
Manual welding is a fairly simple calculation, at least in the direct costs. You have some relatively minor capital investment and some standard overhead adjustments, but by in large, the majority is labour tied directly to each item. Automation of all types is the complete opposite, with the production cost predominantly made up of capital and order overheads; all grey areas to how exactly these will play out.
Reduction in Labour
The general rule is a robotic MIG/MAG system will lay filler at about 3x the rate of a person. Larger or more complex robotic welding systems also often have part positioners or rail-mounted robots for additional reach and maintaining optimal torch angle. In addition to welding outcomes, these also allow a robot to move around a large part much faster than a person moving around a bay and in some cases, the output could exceed 5x the manual rate.
Scalability
The increased rate from a robot allows a higher output with your existing facility and resources. Skilled welders are getting harder and harder to recruit. In the extreme case installing a robot allows you to increase your welding capacity by the same as finding another 7-10 welders; even on a smaller single-shift SME scale, you’re adding the production capacity of at least three welders.
The higher production from a robot further means an increased output from your existing floor space. A common sales pitch is you can make the cells very compact, but it does make the cell more complex to operate and program, so avoid this if possible. Keep the cell to a reasonable size, making its operation simpler yet still capturing a good production rate for the given area. If you are pressed for floor space and are manufacturing towards large production or even repeat high-mix production runs, then you lean on your integrator to safely handle the additional complexity with ease.
Improved Repeatability, Consistency and Quality
The quality and consistency of the welds from robotic automation is one of the golden benefits that many companies are already well aware. Multiple facets lead to this quality; robotic welding power sources from repeatable brands are nowadays highly advanced, with complex current and feed control features offering a very high degree of heat, penetration, and filler control. The other side is the robot motion is incredibly accurate, smooth and repeatable; in essence, the perfect set of hands 24/7.
Reduced or Complete Removal of Downstream Processes
In a number of cases, the quality difference is not just reducing tidy-up but the seam quality improving such that they can be left untouched as cosmetic features to customers.
Reduced Wastage
Improving the quality of the welding operation leads to reduced scrap factors from welding processes or, worse, found later in final QA checks. This includes not only the scrapped parts but the associated labour, consumables, and production utilisation to make that scraped part.
Hazard Reduction
The welding environment is not a clean and safe environment for manual welders. There are immediate hazards from the heat, fumes, and arc-flash, as well as the generally just dirty and unpleasant working space. Long-term damage is known from carcinogenic fumes, reduced breathing capacity, eye damage and exposure to hazardous chemicals. Pair an experienced welder with multiple robotic welders, and you remove the person from that environment.
Robotic Welding Considerations
There are a number of points to consider if your operations are reading for robotic welding.
Is there sufficient work and growth in your market to capture the productivity gains
The production rate and the continuous operation of the system is what will provide the rewards. Manual welders cannot match the production rate of the robotic welding system, but you still need to have sufficient work for the robotic welding system to provide a return. The ROI on production numbers may look great, but if the robot finishes its days’ work in two hours, you probably need to find more work to feed it. One benefit this can, however, provide is high production capacity sitting in reserve for large production runs. So, if you can pay the robot off with single shift operation great, and if you get a spike or large growth, you get the 2nd or 3rd shift for free.
Incoming Quality Control
One advantage still in the hands of manual welders is the ability to adapt to tolerance stacks and poor fitment. If you’re having fitment issues prior to robotic welding, you need to fix those issues first. The general rule is you want the fitment to be within 1mm, ideally less for the robot to work flawlessly without any special functions, and certainly less for thin gauge applications.
Robotic welding systems often struggle with poor fitment and varying dimensions. While dimensional tolerance can be handled with robotic systems, it will increase equipment cost or cycle time. In addition to real-time welding guidance, adaptability tools and other smart features can be added to your cell to check incoming and ensure outgoing quality. On the cheaper end of these are technologies such as jig-based sensing, robotic touch, or simple profile-checking lasers to verify critical features. On the advanced end of the spectrum, options exist to check correct fitment and inspection of exterior weld seams by laser scanning. If you’re in heavy transport or aerospace industries, various automated ultrasonic imaging options also exist for internally inspecting multi-pass welds.
Design for Robotic Welding and Automation in General
Design for manufacturing is a well-known concept across many successful manufacturers of all sizes; design for automated manufacturing is the next level. When parts are produced with automated systems, you need to be aware of the limitations compared to people and how to develop towards the automation strengths. In addition to tighter quality control, you also need to factor into how a robot will reach into weld seams; the order required to control warping and weld jigs should be actively included in the part design. You want to consider how to best load and unload parts into jigs, and the commonality of weld features across part variants to increase code reuse.
Upstream and Downstream Processes
Your production process likely has to change to maximise ROI from the robot system. Imagine if you took your current production, then tomorrow your welders suddenly started welding 3x faster than before? A great problem to have, but the outcome would likely be chaos in the immediate future, and this is best solved before the robot gets turned on.
There are the obvious challenges of avoiding a bottleneck somewhere in your production, limiting the true output of the new flash robotic welding system but additional factors need to be considered when transition to any form of automation.
Direct Processes
In the immediate vicinity of the robotic welding system you need to consider how to load and unload parts. The manual (un)loading of a single station is a simple and low-cost solution, however, limits the production time of the robot, and you need to consider this in the overall ROI picture. More efficient options have multiple welding stations to provide alternating welding/manual (un)loading operations to keep the robot in operation. You can also consider automated means of loading in high volume or fixed production. In the correct application, automated handling can add significant rate, stability, and safety improvements to your operation. Including automated handling can be achieved with additional robots, or in some cases, the same welding robots can pick components from additional stations and, once complete, place them elsewhere. In reality, most NZ and Australian applications will be high mix / low volume scale of operations, which is more suited to the more flexible multiple station cells. Multiple stations are often a good option to get the most from your robot, but you need to consider the part mix and cycle times to verify you get return on the additional expense. If your typical part takes 5 minutes for the robot to weld; and 5 minutes to swap out, this would be an ideal application to feature multiple stations. On the other-hand, if the part requires 10 minutes to weld and a minute to swap out then the ROI for additional stations is limited.
Indirect Processes
Further you need to consider the wider picture and look at possible internal and external disruptions. Internally you want to consider buffering between manufacturing and QA checks as soon as complete rather than prior the next step. This de-couples each process so any stoppages are localised, and this also helps human/machine interaction. Staff have breaks through-out their shifts or maybe overloaded from down members some days; you don’t want your automation to be idle while they’ve having a coffee. Those that are committed to Lean and Just-In-Time manufacturing processes will for the immediate future need to considering adding some safety margin until existing processes are verified or improvements confirmed. If your suppliers are late or you receive unacceptable parts, then you have minimal time to take corrective action before your production grinds to a halt. Your assembly and logics operations are going to be quickly overrun if they get a hold up.
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