Steck Depositors, a leader in food industry robotics, required a solution to ensure smooth and precise guidance of the end effectors for its delta robot system in a sandwich lidding application. Steck sought a low-maintenance, reliable, and corrosion-resistant solution that could handle short travel strokes and high accelerations in a challenging food industry environment. This included the need for quick disassembly of parts to allow for cleaning and washdown at the end of every shift, followed by quick assembly to return the system to service. Hepco’s SL2 stainless steel linear guide was the ideal choice.
Says Mike Wilkinson, Managing Director, Steck Depositors Ltd: “From the point of initial contact, it became clear that Hepco’s products met all our key requirements, while also providing proactive technical and commercial support.”
Steck’s DR2 and DR3 robots, the food industry’s first manoeuvrable ‘wheel up’ robots, use a vision system to detect the position of each sandwich lid, enabling the robot to pick up the lid, rotate it 180°, and precisely place the lid on the corresponding sandwich half at speeds of up to 50 sandwiches per minute. The core linear requirements of this application are straightforward: to guide the robot arms to pick up the sandwich halves. However, the application had several specific demands that not all systems could meet.
EXPOSED BALL BEARING SYSTEMS COULD NOT BE USED
Steck considered using ball based linear technology, such as ball bushings and ball rails, but quickly ruled them out for several reasons. The main reason is due to the open design of the recirculating ball mechanism which requires the internal balls to make direct contact with the guide rail. Rigorous cleaning procedures involve washing out the internal components and passages of these systems to eliminate food traps, which not only washes away the internal lubrication but also risks damaging the unit due to the small balls and flexible components inside the block. There’s also the possibility of parts falling out during cleaning. Additionally, there would be no guarantee that all potential food traps have been fully cleared after the process. Recirculating linear guides rely on internal lubrication for optimal performance and longevity. Running them dry can lead to accelerated wear and, in some cases, could lead to failure of the recirculating system resulting in seizure and component failure.
In contrast, the SL2 stainless steel guide system features Hepco’s proven V guide technology, making it ideal for food production environments where frequent equipment washdowns are essential. The SL2 V guide bearings are sealed and lubricated for life, which prevents internal lubrication being lost, allowing easy cleaning of the system.
Carriages using V guide bearings can be easily removed from the end of the rail without mandrels, which are typically required by most recirculating block technologies to remove the block from the rail. The SL2 system can be returned to the rail just as quickly after cleaning, resulting in reduced turnaround times during the cleaning process.
Additionally, Hepco’s V guide bearings can run dry if needed, albeit at a limited duty, but will not critically fail in the same way that recirculating technology could. Steck reports that many customers don’t re-lubricate the SL2, and the system continues to function reliably.
HIGH DUTY
This application demands short travel strokes and high accelerations of 4G – requirements not every system can meet. SL2 delivers speeds up to 5m/s and dynamic accelerations, perfectly suited to the rigorous demands of this application.
SUITABLE FOR WASHDOWN
Cleanliness and frequent washdowns are critical for this application, including harsh chemical cleaning solutions. With hardened stainless steel slide rails, SL2 reliably withstands Steck’s rigorous chemical cleaning processes, ensuring long-lasting performance with minimal maintenance. Flat, double edge slides are used, with the smooth, easy-to-clean design minimising food traps.
LOW MAINTENANCE
Low maintenance is essential for Steck to avoid costly downtime. This principle is at the core of Hepco’s products, designed to minimise service intervals and enhance reliability, ensuring smooth and uninterrupted operation.
Featuring V guide technology, SL2 has a self-cleaning action that expels debris, keeping machines running. Lubrication devices provide hassle-free operation with long lubrication intervals, or SL2 can run dry if needed. Indeed, while Steck’s customers are encouraged to add lubrication, they understand it’s not always part of regular maintenance. Steck also reports a very low demand for spare parts from their customers, with SL2 slides still not requiring replacement even during the 20 million cycle service, highlighting the system’s exceptional reliability and low maintenance needs.
Adjustable eccentric bearings help further minimise maintenance requirements. When signs of wear appear, the eccentric bearings can be adjusted to eliminate any play, returning the system to its original running condition. Not only does this ensure the robot’s movements remain precise, but it also extends the lifespan and lowers the total cost of ownership of the SL2.
THE SOLUTION IN DETAIL
3 x Flat Double Edge SL2 Slides are bolted to stainless steel ladders, spaced equidistantly, forming the Delta robot’s main framework. At the top, 3 x motors convert rotary motion into linear drive via toothed belts, which are tensioned and maintained on the carriages.
Each carriage, fitted with 2 x Hepco concentric bearings and 2 x Hepco eccentric bearings, runs smoothly along the slides. A ‘dog bone’ connects the carriages to carbon fibre arms, which control the X,Y motion of the end effector by adjusting the motors’ speed
Lubrication is provided by Hepco’s SSLB25F lubricating felts, containing FDA approved lubrication. These felts are fitted to add lubrication to the rails precisely where the bearings travel.
SUMMARY
There are currently over 60 Steck Delta robots equipped with SL2 across 7 sites within the UK. In addition to the sandwich lidding application, Steck’s DR2 and DR3 delta robots solve some of the food industry’s most challenging tasks, including wrap gluing, spreading and spraying pizza sauce, adding sauce to spare ribs, depositing patterned mashed potatoes for ready meals, and picking & placing filled punnets.
Hepco’s SL2 delivers precise, smooth, and repeatable movement of delta robot arms in these high-speed, high-precision food industry applications, all while ensuring low maintenance for maximum efficiency.
