Rationalisation of Blade Range for a Growing Rotary Topper OEM

Rationalisation of Blade Range for a Growing Rotary Topper OEM

Grass Cutting

Overview

Chapmans were approached by a family-owned European rotary pasture topper OEM as they commenced an export sales drive.  Faced with trying to win market share from the brand leaders, they understood that their blade offering required improvement and felt that our Know-How and experience would be invaluable.  Machines with folding mower decks in widths of up to 7.3 metres are available – all known for their solid design and build quality.  Particularly noteworthy is the unique blade holder: a traditional sandwich design with swinging blades clamped between two plates is augmented by additional strengthening, together forming a heavy-duty fabrication.    

Issue

Without in-house hardness testing facilities, our client had unknowingly received deliveries from the traditional supplier which had worn excessively in the field.  Furthermore, multiple lengths of blade, both formed and flat, with different profile shapes and different material sections were offered – despite having the same fitment parameters.

Design Brief

Initially, the commercial teams of the two businesses worked together, organising the blades into two definable product families: straight-sided and profiled. This revealed conflicting specifications calling for different material grades and different tolerances within the same family.  These were now standardised by engineering departments.  It was also decided that a uniform material thickness should be applied – the thickest possible section was selected to ensure a robust product in line with other features of the finished machine.

Our Proposal

Early in the project, we recommended the use of our own grade boron steel which is specially produced for Chapmans by a leading steel mill.  When processed using our PLC-controlled heat treatment system, this allows optimum hardness, often in excess of 50 HRC, yet without risk of fracture given the additional tempering process.  This extended the wear life – in particular of the profiled blades – compared with the previous cold-forming supply route.  Cutting bevels were applied to the raw blade by pressing in a tool, rather than by expensive milling operations, which also maintained the integrity of the material edge.  To rationalise the range, bevels were pressed on each side of the straight blades, creating a universal design, rather than separate right and left-hand versions.  SPC studies during trial batches allowed us to define manufacturing tolerances and perfect the tooling, ensuring a sharp blade capable of cutting grass and all types of vegetation.

The Result

The range of blades offered was simplified as per the original brief and the client also benefitted from increased hardness and an extended wear life.  Chapmans are now the sole supplier for these product families and, thanks to our technical expertise, will be consulted as further prototype designs are developed for external manufacture.

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