Robotic Sealing Automation for Smaller Industrial Operations
by Paul Cutean, Process Manager – Sealer Technology, ABB Inc., Robotics Division
ABB Inc. Posted 03/16/2009
Historically Sealing robots have been utilized in many applications that require tough ergonomic and environmental conditions. An industrial robot’s design and flexibility offer many advantages over the difficult labor constraints frequently posed to a manual operator. The perceived high cost factor has been negated due to many Automotive OEM’s embracing these technologies. Robots, like other computer based equipment, become more affordable as the installed base grows. And with today’s industrial employee workforce having at least a working knowledge of graphical user interface (GUI), the ability to program and control robots has become more intuitive and user friendly for the novice programmer.
The 6-axis robot is a mature, stable product, the primary R&D costs of which have been well absorbed by the manufacturers and early adopters. Sealing robots are now positioned to help general industrial users increase competitiveness, product quality and workman safety, all while reducing the environmental impact associated with applying many sealing materials.
This article will help answer:
- History of adhesives and various types of robotically applied sealer applications
- What is a sealing robot?
- Is your factory a good candidate for robotic sealing automation?
- If so, what advantages will automation bring to your operation?
A Briefing on Adhesive History
The dictionary defines adhesive as: “a substance capable of holding materials together by surface attachment”. This is a simple definition for a material that is the basis of a multi-billion dollar industry with more than 750 companies competing for a share of the market. The first evidence of a substance being used as an adhesive dates back to 4000 BC. Archeologists have discovered broken pottery vessels that were repaired with sticky resins from tree sap.
The era of plastics began with the introduction of Bakelite phenolic, a thermoset plastic, in 1910. Within a year, adhesives using phenolic resin were put on the market. The 1920’s, 30’s, and 40’s saw many new plastics and rubbers synthetically produced, many out of a urgent necessity- developed during World War II.
Although adhesives have been known for about 6000 years, most of the technology of adhesives has been developed during the last 100 years. The development of plastics and elastomers has rapidly advanced the development of adhesives and has given formulators a wide variety of products that can change and improve various properties of adhesives such as flexibility, toughness, curing or setting time, temperature and chemical resistance. Below are typical examples and applications for various types of adhesives that could be robotically applied:
- Animal Glues – made from the protein extracted from the bones, hides, hoofs and horns of animals by boiling. Its major use has been in the wood and furniture industry.
- Fish Glue – is similar protein based glue made from the skins and bones of fish. An exceptionally clear adhesive can be made from fish and was the first adhesive used for photographic emulsions for photo film and photo resist coatings for photoengraving processes.
- Casein Glue – is made from a protein isolated from milk. Its first use was in bonding the seam of cigarette paper. It provides a fast setting bond that requires very little adhesive, one gram of adhesive can bond 2000 cigarettes.
- Starch (Paste) – a carbohydrate extracted from vegetable plants such as corn, rice, wheat, and potatoes. Major use area is in bonding paper, and paper products such as bookbinding, corrugated boxes, paper bags, wallpaper paste (non-removable), also used as a sizing in textiles.
- Rubber-based solvent cements – made by combining one or more rubbers or elastomers in a solvent. Used in a variety of applications such as: contact adhesive from plastic laminates like counter tops, cabinets, desks, and tables. Solvent based rubber adhesives have been the mainstay of the shoe and leather industry.
- Epoxies – made by complex chemical reaction. Various resins are made synthetically by reacting two or more chemicals. Epoxy adhesives can bond a wide array of substrates with high strength particularly metals. Epoxy can replace some traditional metalworking methods of joining like nuts and bolts, rivets, welding, crimping, brazing, and soldering. High strength epoxies are used to construct rotor blades of helicopters, attach aluminum skins to the struts of aircraft winds and tail sections.
- Hot Melt – are thermoplastic polymers that are rough and solid at room temperature, but are very liquid at elevated temps.
- RTV Silicone – is a rubber like polymer called polydimethsiloxanes. RTV stand for room temperature vulcanizing, or simply a rubber that cures at room temp. When cured, silicone rubber adhesives/sealants have excellent resistance to heat (500-600F) and moisture which makes them exceptionally suited for outdoor weather applications, such as sealant caulking compounds in the construction industry. Silicone adhesive/sealants are used to seal windows, doors and portholes on the space shuttle and satellite missiles. A special silicone adhesive is used to bond the heat shield tiles on the space shuttle.
What is a sealing robot?
“Sealing Robot” is an industry term for a robot that has additional fluid handling technologies integrated into the robot which differentiates it from all other standard industrial robots:
1) Sealer Robot Characteristics. Sealer robots are built with numerous arm configurations, meaning that they are manufactured in such a way that they can easily adapt to accessing difficult to reach areas of the part in question. Designing the robots optimal placement with relationship to the part typically yields optimum application results.
2) Fluid Handling Integration. When sealer robots were first designed, they only had one function – to apply materials in a difficult environment. As acceptance and use expanded, sealing robots grew into a unique subset of industrial robots, not just a traditional robot with application equipment. Sealing robots now have the ability to control all aspects of application parameters such as air assist, atomization air, multiple fluid flows/guns/equipments, speed proportional control, and anticipation parameters.
Is your factory a good candidate for robotic sealing automation?
There are several limiting factors to robotic sealing:
- Part presentation
- Amount of dissimilar parts
- Size and shape of the parts
- Amount of material required for the multiple parts
- Various types of material on the same part
Part presentation: Robotic sealing does require a repeatable part presentation window, the part presentation is routinely handled by the following methods, guiding or trapping a part via mechanical methods. Alternately robotic vision systems are utilized to guide the robot to a nominal location on the part. Sealing applicators usually require a tip to part distance of 5mm to 150mm. The more accurately a production conveyance presents a part to the robot, the more benefit of quality and material savings can be achieved. An industry standard request of part presentation can be assumed at +2mm to +75mm, the latter typically requiring a vision solution. The importance of tolerance will vary depending on the precision of application required and cost of sealing (material savings). For most standard applications a simple pallet pin method part presentation provides enough stability/repeatability to make robotic sealing automation accurate and affordable.
Amount of dissimilar parts: Robots are very effective in a variety of sealing systems; from those that involve only few parts to those that involve many hundreds of different parts. The primary environment where robots are not as effective is in ‘job shop’ applications. An engineered piece that will be manufactured one time and never again is not a good candidate. Parts that will be manufactured over and over, even with major time gaps (months/years) between runs can be easily sealed with today’s robotic technology. The robot memory will store part specific programs indefinitely and call for them when required.
Size and shape of the parts: A good rule of thumb is that if a factory operator can seal a part there is a robot that can seal the same part. In certain applications, however, the size or shape of part is so unique that both factory operator and robot may struggle to reach all areas that require sealing. Other Limiting factors include:
- Very small parts: often the work is too fine to be done by hand or robot; some other process such as heat cure will be more effective.
- Very large parts: the robot will need to be moved by additional track systems and extensions to reach all areas; often not viable for a smaller industrial operation.
What advantages will automation bring to your operation?
Quality and sealer material savings: Increased and more consistent product quality is the most widely regarded advantages gained by robotic automation of all types. For sealing robots the most complete analysis must be identified by close examination of the production cycle as the quality improvement cascades through the entire production system.
An industry standard assumption is that a material savings of 5 to 50% is achieved when manual operations are replaced by automation. This savings is achieved in three primary areas:
- Application geometry accuracies of ± 0.5mm are common with robotics. If a substrate requires 4mm diameter + 2mm/-1mm and is regularly produced by hand at 5 - 6mm a material ‘loss’ of 20 - 50% can impact the producer with no knowledge of the additional expense. If the manual operator applies below minimum (e.g. 3mm) the part will need to go through system re-work or pass through the system undetected resulting in a leak or defective part or possibly causing additional warranty claims and or damage to the associate operations. It is much more common to see the over application situation because that generally meets the minimum application requirements thus resulting in manufacturing compliance.
- Trigger accuracy is the other major quality and savings impact. Industry standards of less than 50 ms trigger time are common. This allows the user to accurately and consistently apply sealer to the part only where required every cycle. When the applicator is repositioning the material supply trigger is off, eliminating material loss due to sealer miss-applied onto the part.
- Manual Clean-up of the part is common place when inaccurate, unpredictable practices are in place during the manufacturing process. It is routinely witnessed that automated operations can deliver repeatable results to less than 3% variation.
Savings achieved through applying sealing operations robotically will relate directly to many other savings:
- Manual Exhaust: Automation reduces stack volatile organic compounds (VOC) volumes.
- Manual Exposure: Eliminate potential long term health effects by minimizing exposure levels.
- Over application: Reductions go directly to less filter usage or material usage.
- Reduced rework: Problems such as under applying and over compensating should be reduced.
- Reduced scrap: Less material to landfill.
GREEN is good: Sealer robots have always been environmentally friendly. It is becoming obvious that carbon footprint impact will soon be the baseline for a good community employer, if not legally measured. When using robots there are the environmental savings already discussed, plus additional energy savings that are to be gained.
People first: All savings aside, many sealer application environments are very unfriendly to the workmen who occupy them. PVC contains chemicals such as mercury, dioxins, and phthalates, are extremely unhealthy. Spraying the same product over and over can also result in a repetitive stress injury. Many employees initially see robots as a threat to their employment. In the case of many sealer chemistry situations, the benefits of moving the robot in and the person out far outstrip the disadvantages. In most cases the employee is moved to a safer, more rewarding position.
While it is difficult to completely assess the installed cost for all industrial sealing situations, as an example, a single ABB robot sealing system can be purchased, installed and be fully operational for $70,000 to $120,000. The cost range is dependent on the size of the robot needed. Depending on sealer usage, labor savings and increased quality/less waste, the full investment can be paid back between four months and one year. A well maintained sealer robot can last for a long time, delivering savings that cover the cost of the system many times over!
The robot can be a great tool, but it is only a tool. The most common mistake is assuming that the robot is a sealer applications expert. On the contrary, it is only a contributor to the application. The expertise comes from competent support staff who keep the robot calibrated and at optimum functionality. With the combination of well trained staff and maintained robots, along with their applications equipment it will be very possible to increase quality and throughput while reducing cost and being a better corporate citizen.
Please contact Mandy Hermes at ABB Inc. Auburn Hills MI for additional information
call 248-391-8400 or visit www.abb.com/robotics.