In the last article, Richard Comely and Lee Kristensen of Ransomes Jacobsen looked at the concept and design phases in the life of a commercial mower. Here, they continue the series with a look at the initial phases of the production process as the mower begins the journey through the manufacturing process at their plant in Ipswich
From bare metal and components
One of the major surprises for many visitors to our manufacturing facility in Ipswich is that we actually make most of the components that go into our mowers. The numerous factory tours we undertake every year provides the opportunity to see all types of mowing equipment, built from the ground up - not assembled from bought-in components as many people expect.
Raw materials and shaping
Raw materials, mainly comprising sheet steel, solid steel bar, square and round steel tubing are the main elements in the chassis of our machines, and it is here that the build process really begins. Different gauges of sheet steel are held in a selection of carousels, which automatically feed into laser or flame cutting machines depending on the type of component being manufactured.
These cut the sheet steel into various shapes with a computer program used to ensure that we maximise the layout of each sheet and produce as little waste as possible. Any waste material is then sent for recycling.
Once we have the component in its 'flat' form, we need to bend it to its correct shape, so the next part of the journey is on to the brake presses, where the flat component is bent to the required shape. These heavy duty machine tools use a selection of dies to form predetermined bends in the work-piece.
Obviously, there are many other components in a modern day mower apart from sheet steel, bar and tube. We buy in many components in their raw state; these could be aluminium alloy or steel, depending on the function they will perform, but all would be to our exacting specifications in order that we can control the quality of the finished product.
Raw castings require numerous actions to turn them into the finished entity. Using a range of CNC (computer-controlled) machines, we skim surfaces, drill holes, bore large orifices, tap holes and thread bar and stud. These machine tools are very sophisticated; for instance, if a machine is drilling a hole and the drill bit goes dull, the machine will sense a change in the resistance of the drill bit. This indicates that it is not cutting efficiently, so it will put the process on hold while it automatically changes the drill bit and the operation will resume.
This is a typical process in any major manufacturing operation, and we are no different. As a reader of Pitchcare, you probably assume that this is a fully automated process, using robot welders. In fact, we have two robots, introduced in the last three years, and the rest of the welding is undertaken by a team of highly skilled individuals using traditional welding techniques.
A selection of jigs are used to correctly set up the items that need to be welded together, to ensure the utmost accuracy. Some of our mowers have very fine tolerances, so it is vitally important that the pieces fit together correctly as they move through the production process.
Visitors to the factory are always fascinated by our Paint Shop. The first thing they see is an overhead conveyor belt with hundreds of different items hung on wire hooks and moving slowly around the perimeter of the paint booth. These can vary from the smallest bracket to a complete mower chassis.
This conveyor belt moves the items around the outside to the first stage, which is the pre-wash. Here, the item moves through a series of chemical and water baths to remove every item of dirt, grease or other contaminant that may affect the finished paint quality.
Once the cleaning process is complete, it continues to the actual painting stage. Our automatic paint process is electrostatic, which means the powder paint particles are negatively charged and the work-piece being painted is positively charged. When the paint particles are sprayed towards the work-piece, they are attracted to the item - similar to two opposing magnetic poles - and completely cover it.
Just in case there are any really awkward areas that could occasionally be missed by the process, we have two guys in the paint booth, complete with breathing apparatus and safety suits, whose job is to spray these awkward areas to ensure a quality finish.
Once the item is fully coated, it then continues on the conveyor belt into the oven, where it is baked and the powder melts and covers the item.
Integrated into the paint booth is a powder recovery unit, which recovers between 95% and 100% of the paint over-spray and this can be recycled for the next run. This electrostatic paint process is hugely more efficient than wet painting and provides a better finish.
In theory, we now have most of the manufactured components ready for assembly of the mower to commence, but we still have the most important component to build.
Cutting cylinder production
A myth surrounding the production process at Ipswich is that we don't make our cutting units, but buy them in ready-made. However, nothing could be further from the truth; we have been building our own cutting cylinders since 1832 and that's why they are among the best in the industry.
A cutting reel consists of multiple helix-shaped reel blades fixed to a rotating shaft. The smaller the diameter of the reel and the higher number of blades will determine that the reel is designed for fine turf. Conversely, the larger the diameter of the reel coupled with a lower number of blades determines that the reel is designed for longer grass.
We begin the construction of the reel by laying out the 'Spiders', the circular discs that support the cylinder blades, in a specially constructed jig. These spiders would have been cut with the laser cutter from sheet steel as described at the beginning of this feature.
We buy-in the blades, made from steel that we have specified and cut to an oversized length. The cut lengths are then passed through a machine that bends them into a helix and the shaped blade is then positioned into the spiders. When in their correct position, they are welded into place and then the blades are cut to the correct length.
The embryo unit is then heat treated and shot-blasted as part of the pre-paint preparations and the shaft is inserted and welded to the spiders.
Situated within the cutting reel manufacturing area, we have a smaller, dedicated paint plant which, again, uses the electrostatic process to apply paint to the reels. It is smaller replica of our larger paint booth, with a conveyor, pre-wash system and powder particle recycling.
After painting, the unit is ground to ensure that it is cylindrical and then balanced in a similar manner to that when a new tyre is fitted to your car. Small lead weights are attached to correct any imbalance, the reel is washed, dried and stacked in bins ready to go to the next part of the production process, or boxed to go into the spares inventory in our Customer Care department.
Bottom Blade production
There is another component that is essential in the construction of a cutting cylinder and that is the bottom blade (sometimes referred to as a bedknife). The bottom blade is the stationary blade, attached to a rigid backing plate, which works together with the rotating cutting blades to provide the shearing action necessary to cut grass.
As you would expect by now, we fashion our own bottom blades here on site.
They arrive here as flat bars in various thicknesses, cut to lengths relevant to the type of cutting cylinder they will be used with.
The bottom blade is heated in a furnace and, once pliable, is then put into a press to form the lip, the leading edge that will work with the cylinder blade to cut grass. A second section on the press flattens the blade to remove any distortions from the heating process. Once cooled, the lip is then ground to give a sharp edge.
The blade is then shot-blasted to ensure a smooth interface with the backing plate and the lip is induction hardened. Following a further heat treatment, the holes for the backing plate fixing screws are drilled, countersunk and the lip is ground again to give it its final edge.
If it is being used on a production mower, it will go to the Machine Shop to be fixed to its backing plate or coated with a preservative, packaged and sent to our Customer Care department for later sale as a spare part.
Cutting unit assembly
If the cutting cylinder is to be used on a production mower, then it has to be assembled into a cutting unit frame. This frame will eventually carry the cutting cylinder, the rigid backing plate and rollers.
The 'box construction' of the frame means that that the cutting cylinder, frame cross members, bottom blade and rollers are straight and parallel to each other and the vertical components - spiders, frame side plates - are parallel to each other and perpendicular to the horizontal components. Slightly complicated, but it means that the unit is true in both planes.
The frame assembly comprises the two side plates and relevant cross members, which are robot welded to form a rigid structure. The first process is to attach the bottom block and bottom blade assembly, insert the rear roller, fit bottom blade adjuster mechanism, insert the cutting cylinder into the frame and attach the bearings to the shaft ends.
Next, we attach the housing for the hydraulic motor and backlap to put an edge on the bottom blade. If required, we fit the front roller at this stage. The entire unit is then set for parallel, grease is pumped into the bearings before being placed into a wash unit to remove the backlap paste.
Decals are applied to the outer casing, and the concaves, which help disperse the grass clippings, are bolted to the unit and the job is finished. The completed unit is then moved to the end station on one of the dedicated production lines for fitting to the relevant mower.
So, that's an overview of the processes that go into preparing the majority of components used to produce a modern day mower. A significant section of this article has been devoted to cutting, bending, shaping, welding and machining components. These are standard operations that you would expect in any manufacturing facility across the UK.
What, I believe, sets Ransomes Jacobsen apart is the ability to produce precision cutting units that provide you with tools to do your job as turf professionals. We're extremely proud of our 'Made in Britain' heritage, and long may it continue.
In the previous feature we looked at the concept and design process, in this article we looked at the production of the various components and, in the next feature, we will focus on the physical building of a mower as it progresses along one of our production lines.