Optimising an Established Design for a Niche Cultivation OEM
Overview
Chapmans were contacted by a manufacturer of rotary spaders based in the Low Countries with niche markets around the world. The machines are used instead of ploughing in areas where only mixing of the topsoil is required, instead of the traditional method of completely turning the soil to a greater depth. Spaders can be combined with a roller or seeder to create a one-pass system – popular not only in areas with open fields such as on reclaimed land but also in lesser developed agricultural economies, where diesel and cost savings are critical.
Issue
The production route for the main spade had not changed in many years, being essentially a fabrication comprising three or more separate pieces. The cutting edges were created by milling, providing dimensional accuracy but reducing the edge strength. Given the large amount of uncontrolled welding, the Heat Affected Zone was significant enabling wear to propagate and reduce the service life of the component.
Design Brief
The client required improved performance from the spades as defined by wear life – particularly challenging in powered cultivation applications. This was especially important as each rotor is fitted with multiple spades resulting in costly downtime if they all have to be changed simultaneously. Despite this, the working depths and widths of the original had to be maintained.
Our Proposal
Given that we were working with established component designs, we focussed on incremental improvements to enhance product performance. Firstly, we pressed the cutting bevels of the spades using specially developed tooling. By compressing the material, rather than removing it by milling, the leading edge maintained its strength and remained effective for longer. Secondly, the angled spade shafts were changed from simple pieces of bar welded together to a one-piece shaft laser cut from sheet steel, eliminating one Heat Affected Zone completely. The shaft still required welding to the spade itself but the amount of surface welding was reduced by adding lugs to the bottom of the shaft aligning with locating holes in the spade. This again reduced the amount of time and heat to weld. As an option, on some models we brazed Armacarb carbide tiles for the ultimate in-service life. Finally, for a more professional brand image, we marked components with our client’s logo and applied paint to inhibit rust during storage.
The Result
The life of the spades has been extended so machines now experience less downtime. Replacing spades less often reduces the overall cost of ownership and users are less reliant on local supply and off-the-shelf spares in-season – helping the client sell machines into geographically remote territories. In a short period of time, Chapmans has become a key supply partner who is consulted regularly for technical support and guidance.
