lineaR motion FeatURe


smooth sandwich assembly HepcoMotion’s SL2 stainless steel linear guide


is delivering smooth and repeatable movement of delta robot arms in a high speed, high precision, sandwich lidding application


A


s a leader in food industry robotics, Steck Depositors required a solution to ensure smooth and precise guidance of the end


effectors for its delta robot system in a sandwich lidding application. A low-maintenance, reliable, and corrosion-resistant solution was needed that could handle short travel strokes and high accelerations in this challenging food industry environment. There was also a need for quick disassembly of parts to allow for cleaning and washdown at the end of every shift, followed by quick assembly. To meet requirements, Hepco’s SL2 stainless steel linear guide was chosen.


linear requireMenTs


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. The application, however, had several specific demands that not all systems could meet. The company considered using ball based


linear technology, but ruled these out due to the open design of the recirculating ball mechanism which requires the internal balls to make direct contact with the guide rail. In addition, 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. There’s also the possibility of parts falling out during cleaning; and there was no guarantee that all potential food traps have been fully cleared after the process. 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.


low MainTenance


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. 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 is essential for Steck, and


this principle is at the core of Hepco’s products. 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, but SL2 can run dry if needed. 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. In addition, adjustable eccentric bearings help further minimise maintenance requirements. When signs of wear appear, the eccentric bearings can be


noVembeR 2024 DESIGN SOLUTIONS 25


adjusted to eliminate any play, returning the system to its original running condition.


The soluTion in deTail


Three Flat Double Edge SL2 Slides are bolted to stainless steel ladders, spaced equidistantly, forming the Delta robot’s main framework. At the top, three motors convert rotary motion into linear drive via toothed belts, which are tensioned and maintained on the carriages. Each carriage, fitted with two Hepco concentric


bearings and two 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, the company explains, are fitted to add lubrication to the rails precisely where the bearings travel.


MeeTing deMands


There are currently over 60 Steck Delta robots equipped with SL2 across seven 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.


HepcoMotion www.hepcomotion.com


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