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ATM Automation offers multiple plastic joining technologies


 
  
 
ATM has, for many years, been recognised as the leading supplier of Robotics and Automation to the plastics industry within the United Kingdom. This reputation has been built upon ATM¡¦s ability to provide a diverse range of technologies and solutions for applications such as de-moulding, parts handling and assembly. With component manufacturer¡¦s now increasingly adding value to their product by performing more of the downstream assembly operations, plastic joining has become a key growth area for ATM. 
 
In house plastics joining development lab 
 
With a history of almost 40 years within the UK Automation industry, ATM has seen many changes, not only in the technologies used in the marketplace but also in the demands of manufacturers and end users. Many companies now insist on a ¡§Turnkey¡¨ approach to their specific application and this brings with it a need for the automation supplier to become much more conversant with a broader range of technologies and processes. This is especially so in the field of plastics joining where it is essential that the correct process is selected based upon the individual application and the materials to be joined. 
 
To ensure the most appropriate process is proposed for any given application, ATM has recently opened its in-house plastics joining laboratory. This new resource, backed by the extensive experience of ATM¡¦s plastic joining specialist ¡V John Neugebauer, enables customer applications to be evaluated ahead of the proposal stage thus determining not only the best process for the application, but also enabling cycle times and process parameters to be defined in advance. 
 
The ATM in-house laboratory has a number of different technologies available for evaluation including:- 
 
- Pulse Staking 
 
- Hot Air-Cold Forming 
 
- Ultrasonic 
 
Each of the different technologies can be tried and tested on the customer¡¦s sample parts to determine the process best suited to the materials under evaluation. In some cases, there will be perhaps two or more technologies which can successfully join the parts. In these instances, depending upon the number of stake points or weld positions, cycle time required and aesthetic appearance required, one technology may then be deemed more appropriate for that specific application. 
 
The plastics joining knowledge resident within ATM, together with the range of technologies available for evaluation, provides the customer with an un-biased view of the different technologies, their characteristics and their likely benefits or indeed drawbacks. 
 
Hot Air-Cold Staking is a traditional joining method which has been used for many years in a multitude of applications. Seen as a simple technology which can be used easily by un-skilled operators, this process is also relatively inexpensive especially where the components have multiple stake positions. The disadvantages of this process however include the fact that for a small number of stake points or tips the process is not particularly energy efficient. The process is not suited to hand held operation and also in some applications, the gap between the hot air nozzle and the stake point is critical if consistent quality is to be achieved. This renders the process less suitable for applications where the component tolerances may not be sufficiently tight. Additionally any concentration of heat energy applied to a confined area containing several stakes may stress relieve a moulded component causing unacceptable distortion. 
 
Ultrasonic welding systems are used extensively for many applications, but as for other joining processes, this too has limitations. When applied to materials with a high glass fill content (40% to 50%) the ultrasonic process can cause particle fragmentation, which is unacceptable in certain applications such as the production of Aerospace or Military components and automotive seat restraint and air bag applications. The use of ultrasonic welding on electro-mechanical components and PCB¡¦s can also pose a problem due to the high frequency vibrations generated, as can the use of the technology in close proximity of metal components. Consideration must also be given to the noise generated by the process, and appropriate steps must be taken to prevent prolonged operator exposure to the high frequency sound. 
 
Ultrasonic welding does however have a number of advantages. It is possible to have a hand held unit which enables the use of the technology on low volume production or where a dedicated multi-tip machine cannot be justified. The process is also quick and can generally be used on a wide range of materials. Where multi tip applications are required, a number of sonotrodes can be operated from a single generator unit by switching from one tip to another in a pre-defined sequence, thus helping to reduce the overall cost of the machine. 
 
A less well known process, pioneered in the United Kingdom by ATM, is the patented ¡§PulseStaking¡¨ technology. Available as a portable hand held device or integrated into multi head desk top or floor standing machines. PulseStaking works by accurately controlling the amount of time a current passes through a specially designed tip which is rapidly heated to the melt temperature of the material being processed. The current is ¡§pulsed¡¨ on and off to ensure that the material does not overheat and begin to degrade. At the end of the ¡§pulsed¡¨ heating cycles, compressed air is passed through a central tube which rapidly cools the tip and allowing the plastic to solidify rapidly. The small heat affected zone around the PulseStaking tip, plus the fact that the process does not generate any vibrations, makes PulseStaking ideal for applications on electronic components and PCB¡¦s. The process is also unaffected by the close proximity of metal components and the controlled nature of the heating cycle also makes it more suitable for materials which have a high filler content. 
 
Hybrid machine 
 
Selecting the most appropriate process for an individual application can mean that on occasions two different technologies will be used together within a ¡§Hybrid¡¨ machine. One such example was a rotary table welding machine designed and built by ATM for the production of powder print cartridges. This machine employed ultrasonic technology to weld a plastic cap onto one end of the cartridge housing whilst a multiple tip Pulse-Stake heat staked an ID tag in the form of a small PCB at the other end of the assembly. With a very localised heat affected zone and with no vibrations generated from the process, Pulse-Staking was deemed to be the most appropriate technology for this part of the assembly process. This ¡§Hybrid¡¨ machine operates very successfully and is an excellent example of the unbiased approach adopted by ATM for every individual application. 
 
ATM also has experience with other plastics joining technologies such as Hot Plate Welding, Vibration Welding and Laser Welding. With a track record of applying the various technologies in the field, together with the accumulated knowledge gained from a multitude of different applications, ATM is uniquely positioned to provide expert advice on the most appropriate joining technology for all plastics applications. 
 
ATM Automation also manufactures a range of Cartesian Robot Systems for use within the plastics moulding industry. ATM is a turnkey solutions company and provides fully integrated systems using Cartesian robots, 6 axis robots and assembly automation technology. 
 
 
 
 
 

ATM Automation Cuts Through Polypipe's Flash Problem


 
  
 
As a highly respected systems solution provider to the plastics industry, ATM has been involved in many diverse and challenging applications. However, when Polypipe asked ATM to devise an automated solution for the removal of flash from their range of blow moulded RIDGIGULLY products, ATM were presented with a highly unusual combination of Design, Process and Health & Safety challenges. 
 
Polypipe Civils is the UK's leading manufacturer of surface water drainage, sewerage, cable protection systems and water management solutions, serving the utilities, construction, civil engineering, agricultural and sports and leisure markets. As part of the Polypipe surface water drainage system, RIDGIGULLY products are blow moulded in HDPE (High-density polyethylene) in 3 different sizes. The post moulded products incorporate significant amounts of flash around the mould joint line which traditionally, has been removed manually. The largest of these parts weighs up to 12kg and with some areas of flash being up to 12mm thick, as a manual process, this was both time consuming and arduous. 
 
Following a review of various flash removal processes and automation concepts by Polypipe, ATM were chosen to provide a fully automated flash removal system based upon a six axis robot and a laser. The combination of a laser with a six axis robot is not in itself new, and indeed ATM already had previous experience of building systems of this type for automotive industry customers. Automotive laser cutting applications, by their very nature, are fine tolerance, and whilst this demands precise programming and robot path control, the fact that the components have clearly defined datum points means that the laser and robot together can easily meet the dimensional and profile tolerances required. There are however a number of distinct differences between these automotive projects and the Polypipe application, not least the larger tolerance band of the blow moulded part and the material from which the part is produced. 
 
Meeting the challenges 
 
From the outset, this was clearly going to be a demanding application and ATM was determined to ensure that the system specification reflected the challenging nature of the project. With three different sizes of product to be laser cut (300mm, 750mm and 900mm) and a requirement to not only remove flash from the moulding, but also to cut two 360 degree paths, ATM determined that the optimum solution would be for the robot to hold the part and manipulate it under a fixed laser cutting head. A six axis robot system with a horizontal reach of 2,000mm and a payload capacity of 50kg, was chosen to provide the working range and handling capacity required for these large components. 
 
ATM chose Rofin-Baasel UK Limited as the supplier of the laser system, based upon their extensive application experience and the excellent reputation for reliability of Rofin CO2 lasers. A diffusion cooled slab laser with an output power of 2,500W, was selected for the project. Detailed consideration also had to be given to fume extraction and filtration for this project, as the parts being cut are produced from 100% regrind material. This means that the blow mouldings can contain a number of contaminants which could have a detrimental impact on the performance of any extraction and filtration system. Following a series of trials, a multi stage dosing filter system was developed, with the air extracted from the cell being dosed with Calcium Carbonate before reaching the filtration system. To minimise the time associated with cleaning filters and removing debris from the filtration system, two sets of filters were incorporated. This enables one set of filters to perform a self cleaning cycle, depositing any dust and debris in a bin, whilst the system continues to run using the second set of filters. 
 
The work-cell concept incorporates two component fixtures at the operator load and un-load station. This enables the robot to deposit a completed part and immediately pick up a new part ensuring minimum time is lost between the laser cutting operations. With an internal safety door closed to protect the operator, the finished part can be manually removed and another part loaded for processing by the robot. The robot gripper system and the component location fixtures, incorporate quick change tooling features to enable the system to handle the three different product sizes produced within the cell. 
 
Focused on success 
 
The challenges of this project were not just limited to selecting the most appropriate hardware for the task in hand. The dimensional tolerances from the blow moulding process also had a part to play in the final solution. 
 
The RIDGIGULLY components required flash to be removed from all areas around the mould tool joint line, and in places this flash can be up to 12mm thick. In addition, to enable the flash being removed to be re-processed more easily, the larger areas of waste material had to be cut into smaller pieces. This required intricate programming by the ATM engineers to achieve the balance between reducing the size of the waste material and maintaining the target cycle time. 
 
The major issue yet to be overcome in this application was the need to produce trimmed components with a minimum of excess material, on components which have potentially large part to part variations in size. The variation on each component meant that it was not possible to establish a consistent datum position, from which programme offsets could be generated, and this led the ATM engineers to develop a highly unusual but extremely effective solution. 
 
In almost every laser application, the beam is focussed to a fine spot, at a particular distance from the nozzle or optics, to generate a small spot size and enable precision processing of the part. Even with a powerful laser such as the Rofin DC025 a spot size of 1.0mm is achievable at the appropriate focal distance. This application however did not require such degrees of accuracy, due to the variations in part tolerance, and ATM turned this to their advantage. By developing clever programming techniques and using the laser “Out of Focus”, a larger spot size was achieved. Using the laser outside of its focal point would require more laser power to cut the material, and ATM’s initial choice of a 2,500W laser proved to be a major contributing factor in developing this final solution. The larger spot size together with the higher power settings on the laser enabled the system to not only achieve the cut profiles required during flash removal, but the high temperatures reached during the trimming operation also partially melt the cut area providing a smooth aesthetic finish on the part. 
 
Polypipe has achieved their objectives of turning a labour intensive and arduous task in to a cost effective and highly reliable automated solution. ATM has also clearly demonstrated that difficult and unusual automation applications can become a reality using a combination of field proven hardware lateral thinking, and a determination to satisfy the customer’s requirements..
 
 
 

ATM SCOOPS 6 AXIS ROBOT DEAL


 
  
 
ATM Automation Limited, the leading manufacturer and supplier of robots and automation to the plastics industry, have recently installed 3 off ATM Nachi 6 axis robots into an application that would have been historically considered the domain of 3 axis robots.
 
The application involved installing these robots next to 3 separate injection moulding machines in an area with quite restrictive space constraints.
 
ATM Automation was chosen from several suppliers considered because of the quality of the robots together with ATM’s ability to supply and integrate further automation at a later date. The service and support facilities that ATM can offer were also major considerations.
 
Mr Geoff Lomax – Engineering Manager of Sangenic International who make the Tommee Tippee Nappy Wrapper for worldwide distribution says
 
“Our moulding machines and robots were due for replacement. Rather than simply replace the old 3-axis robots we chose to upgrade our capabilities with automation in mind. Currently, the 6-axis robots are tasked with de-moulding highly polished components but in the future they will form the centrepiece of our automated assembly cells.
 
By investing in the superior capabilities of these robots now the cost of future automation is significantly reduced. The versatility of these robots means they can be simply re-tasked as products develop or change. If required, they could be easily moved off-line to carry out other assembly or packing operations.”
 
Jason Shuttlewood – Sales Manager for ATM explained that ATM are in a unique position, as a manufacturer of 3 axis robots and a leading integrator of 6 axis robots, to offer their customers an unbiased view on the best option for them and he says
 
“We have found that while the number of new moulding machines and hence requirement for new robots for standard pick and place applications remains fairly static this year (although still important), there has been significant growth in other areas of business.
 
These are mainly split into 2 areas.
 
The first is a significant increase in robotic automated cells that integrate additional processes into the system to reduce the labour cost and increase efficiency. Typical applications include insert loading, packing, in mould decoration, assembly and degating.
 
The second growth area is cell enhancement whereby we automate these processes around an existing robot and moulding machine. The rational again being to reduce costs and improve efficiency.”
 
The Nachi robot is well established among major Japanese automotive OEM’s in the UK and has become increasingly popular in the plastics sector.
 

ATM ROBOT INSTALLED AT FLEXIBLE LAMPS


 
  
 
An ATM six axis robot has been employed at Harlow-based Flexible Lamps to load L-shaped pins into similarly shaped recesses in injection moulded housings for commercial vehicle side marker lamps.
 
The robot is part of a production cell incorporating a Negri Bossi NB 160 tonne machine, which moulds the ABS housings in a twin impression tool on 32 second cycle. The mouldings are first extracted from the tool by the robot, located at the rear of the machine, and precisely positioned on a jig. Moving simultaneously in three axes, the robot then picks up a pair of pins from a linear track leading from a bowl feeder and carries them over to the housings.
 
Wrist rotation through 45o is then performed and the pins are lowered into the recesses in this orientation. When the pins almost reach the bottom of the recesses, the wrist is rotated to its original position and the components are accurately deposited into place. They are then released and the robot withdraws.
 
ATM and Flexible Lamps co-operated closely in developing the cell, which was set up and tried out at ATM’s Leicester factory before delivery to Harlow. This ensured that only fine tuning was required when the equipment was delivered and commissioned on site and minimised make ready time.
 

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