Devon-based XYZ Machine Tools is helping Sweden-based Handicare to maintain the accuracy, rigidity and quality of its stairlifts by enabling it to machine the mating surfaces of its tubular components at its UK factory in Birmingham using an XYZ RMX 3500 for straight sections and an XYZ RMX 4000 for curved sections to achieve the perfect fit.

Handicare is a leader in its industry covering accessibility, patient handling and vehicle accessibility and can trace its roots back to 1886. Its objectives are to offer solutions and support to increase the independence of physically challenged or elderly people, and to enable them to live an active life on their terms as well as to provide help for their care providers and family.

Handicare’s sells its products and solutions globally — currently in more than 40 countries. Of the Group’s total revenue in 2020, Europe accounted for 71%, North America 28% and the rest of the world 1%. The company designs and manufactures straight and curved stairlifts, producing more than 50 every day at its Birmingham factory in Kingswinford. Each stairlift is bespoke as they are designed to fit customers’ unique stair configuration.

The key element of each stairlift is a pair of tubular runners with gear racks welded to them. These support the seat and, with its pinion drive and rollers, allow it to transport the customer smoothly and safely between floors. Each set is unique and carefully designed to fit the stairwell.

During the design phase, consideration has to be given to handling the tube sections and accessibility for installation and assembly. This means that the set of tubes needs to be made in sections ready for assembly on site. Some shapes for curved stairlifts can be complex, for example moving the seat to a park position around a newel post, so these need particular care during the manufacturing process.

Robot-welded
Nabil Mohamed, Handicare production engineer, explained: “For straight stairlift sections the tubes and gear rack are robot-welded together and they are then cut to length. We leave an excess of 0.5mm which is then machined off on the XYZ RMX 3500. We do this to make sure that the gear profile on the rack is perfect when we join the tubes. If we didn’t do this and left a slight mismatch on the gear profile, the customer would feel an uncomfortable jolt every time the seat went over a joint.”

The XYZ RMX 3500 is dedicated to straight sections and has a set of fixtures on the bed each designed to lock into the gear profiles to position the tube in the exact position required to mill across the end and generate an accurate gear profile and perfect tube length. The open design of the bed mill makes it possible to work with long tube sections which overhang the bed. The machine’s ProtoTRAK control has the different programs already prepared so that it is easy to select the one required for the fixtures being used.

For curved profile stairlifts, the process is similar with tube sections being machined on the XYZ RMX 4000. This has a larger bed 1,474 x 355mm and has fixtures loaded to suit the machining the ends of curved sections, again locating the tubes on the gear rack to ensure end machining is accurate.

Further special purpose machinery cleans the burrs inside and outside the tubes, while etched marks on each component give reliable identification. To join tubes, straight sections can be connected with crimped inserts and cross drilled bolt holes, while curved sections are robot welded together with an internal collar. Special purpose machines clamp components together for these operations to ensure on site assembly goes smoothly before physical inspection and surface finishing.

Mr Mohamed concluded: “Every component goes through one of the XYZ RMX machines, so they are a crucial part of the process, and their record of reliability is very important to us. Being able to accurately machine the ends of every tube and gear rack is a vital part of the quality, performance and reliability of our products.”