By DE Editors
With its two-hinged handle, the Senior & Dickson collapsible shovel is designed and manufactured with the help of specialist CADCAM tools from Vero Software.
Senior & Dickson specializes in plastic injection, rubber molding and die-casting. By linking its experience of injection molding, tool making and rapid prototyping, the UK-based company readily develops ideas from concept through to working prototypes and on to production tooling, as demonstrated by the snow shovel project.
While the snow shovel is primarily aimed at motorists because of its handy folding design, the manufacturer also expects it to become an essential tool for helping householders keep their driveways clear of snow and other debris with its exclusive interchangeable shovel and fork heads.
The VISI suite of CADCAM software was instrumental in designing these head configurations, specialist handle and 3D tooling, along with the CNC toolpaths. All design work and electrode extraction is performed in the CAD office, while toolpath generation is carried out on the shop floor next to the milling machines.
Senior & Dickson Technical Director Chris Hodgson explains the advantages of taking the toolpath creation out of the CAD office.
“We moved the CAM onto the shop floor, as the machinists are closest to the action and can react immediately without having to wait for the design team,” Hodgson says. “They know what tooling is available and how to best machine an insert or electrode.”
The electrodes are extracted directly from the 3D inserts by the CAD office and passed to the shop floor for manufacture. The graphite electrodes are machined using Hurco Ultimax VMX50 machining centers (50x26x24-in. machining envelope) and then sparked into the tooling using an Agietron 3U cavity sinking EDM machine.
VISI Modelling was key in both designing the original handle and then strengthening it, by allowing Senior Design Engineer Karl Freeman to add further ribbing to the existing model and easily apply the changes to the tooling inserts. Based around the industry standard Parasolid kernel, VISI provides complete flexibility to construct, edit, deform and repair complex 3D data. Hodgson notes that after trialling the first prototype, the team chose to add cross-ribbing to the shaft to give it greater sideways strength and apply larger radii to remove a localized stress point, which caused part failure during stress testing.
“This was very easy to do in VISI because the software is not constrained by rules or a previous design history,” Hodgson says. “You can simply jump back into the design process any point "you’re never stuck with a model that you can’t alter.”
Once the model had been finalized, the 3D tooling was designed using VISI Mould. It was then manufactured from P20 pre-treated steel for the shovel head, and H13 hardened steel for the handle and hinge. The shovel handle and folding mechanism are produced using a high-performance polycarbonate; the shovel head is produced using a recycled polypropylene, which is commonly used and resistant to fatigue.
The shovel concept began with a wooden handle, but Senior & Dickson quickly realized that this was impossible because of the angle required for it to connect to the head. The company turned to VISI to design the model for a moulded handle.
“We looked at using a cranked handle, and followed on from that with a folding design to make it much more convenient to store,” Hodgson says. “At around 2 kilos, the shovel is extremely lightweight, and with the folding handle it fits inside the smallest postage bag, keeping post and packaging delivery costs down for online customers.”
Hodgson reports that before switching to VISI from another high-end software system, it often took two to three weeks to produce tooling, but VISI has reduced that time to less than four days. Freeman points out that VISI’s speed and ease of use means the design office is now producing more quality work with fewer members of staff.
Once full production is up and running, the company hopes to supply the new shovel though several home improvement retailers.