There are times when commercial-off-the-shelf (COTS) parts simply will not do the job. It could be due to time constraints involved with shipping from the original equipment manufacturer (OEM), especially if the parts have to come from overseas. It could be a budgetary issue that prevents the purchase of a new part at this time, making a repair or resurfacing a better option. It might be that a part that is no longer in production by either the original manufacturer or any aftermarket suppliers. It could be that a custom part could improve your hydraulic system’s performance and efficiency. Whatever the reason, most facilities that utilize hydraulic systems will eventually need a custom fabricated repair part.

Commonly Fabricated Hydraulic Parts

Virtually any hydraulic part can be custom fabricated. Small items such as hex adapters, hydraulic hose connectors, or end fittings, or larger items such as hydraulic cylinders can all be custom made. It is not unusual for hydraulic motor or pump components such as pistons, swash plates, distributors, and cam rings to require minor surface processing to restore them to OEM specs, as opposed to outright replacing them with a new part. Hydraulic system components often include custom valves and manifolds. Hydraulic cylinders are often custom machined (including boring and honing) and/or welded as part of the repair process or manufactured from metal stock to customer specifications. Parts such as replacement tie rods and fasteners can also be made. Note that design modifications to new OEM or aftermarket parts could also be classified as custom fabricated.

Benefits of Custom Fabricated Parts

When it comes to custom repair parts, there are quite a few benefits. One of those benefits is control over the design. You can choose the materials you want the part made from (within reason, of course) and work with the fabricator to develop the best possible design. You do not have to settle for what the OEM or supplier is willing to sell you. And the customization does not even have to address a major facet of the part, such as the type of material or overall geometry; a modification could be a simple tweak to an existing design, such as a slightly repositioned opening for a fastener or a more generous tolerance to accommodate geometrical differences.

Your facility may have older hydraulic equipment that still performs well and you have no intention of replacing it. However, old equipment can become a problem when the OEM no longer supports it and replacement parts are no longer manufactured. With the option of having custom manufactured repair parts, you do not have to worry about aging equipment that is still in good working order because you can have repair parts made specifically for your older machine.

In some instances, it can be faster (and possibly more economical) to have a part fabricated as opposed to waiting for it to be shipped, especially when the supplier does not currently have it in stock. Both price and speed, however, depend heavily on how complicated the part geometry is, how tight the tolerances are, and what materials are involved in the fabrication process. But if you engage a professional fabrication facility with experienced craftsmen, you might be surprised at just how fast that component can be made.

In many cases the damage to the surface part is minor enough that it can be resurfaced back to spec, or all that is needed is some repair welding. Such an option is far cheaper than purchasing a new part and will further extend the life of the part in question.

Processes Used in Custom Fabricating Hydraulic Parts

There are two major types of process used in the fabrication of hydraulic parts: metal removal processes (often grouped together under machining) and metal joining processes (which includes welding). A component of any complexity will probably require more than one manufacturing process to complete its fabrication.

Metal Removal Processes

Metal removal processes include milling, drilling, turning, and abrasive machining. Turning involves rotating the workpiece to achieve a shape that is typically axially symmetric and is used for tasks such as broaching and reaming. Milling, on the other hand, is often used for parts that are not axially symmetric and may have additional features such as slots or pockets. Abrasive machining includes grinding, lapping, and honing (which are often used to restore material surfaces to specific finishes or flatness). However, abrasive machining can also include newer forms of manufacturing such as ultrasonic machining or abrasive jet machining.

Machining and turning often make use of computer numeric controlled (CNC) machining equipment. This type of equipment supports computer aided manufacturing (CAM) which allows a part to be designed on the computer as a solid model and then machined to great accuracy and precision by CNC equipment. However, not all parts need to be CNC machined — simple parts can often be manufactured far more quickly and to tolerance by a skilled machinist.

And a skilled machinist is needed just as much, if not more, when CNC equipment is utilized. There are a variety of critical parameters involved in machining, including speed of the tools, the feed rate of the workpiece, and the depth of cut for each pass. These parameters depend heavily on the material, type, and shape of the tool; whether or not coolant is available during the cutting process; the material type of the workpiece; and the type of material removal involved. In addition, the type of cutting tool depends on what is being done to the workpiece and the material of the workpiece. If the depth of cut is too deep, the tool may end up broken and the workpiece damaged; if the cut is too shallow, the process will take an unnecessary length of time to complete.

Another aspect of machining involves tolerances, or how much difference there can be between the target dimension and the actual machined dimension. For example, a drawing may call for a 0.5” hole to be drilled into a part. If the diameter of the hole can be anywhere from 0.505” to 0.495”, then it is written as 0.5” 土 0.05”, where 土 0.05” is referred to as the tolerance. Tighter tolerances require longer to machine and tend to drive the cost of fabrication up.

Welding Processes

Welding processes are used to permanently join two pieces of metal together. The most common welding processes include the following: metal inert gas (MIG) welding, tungsten inert gas (TIG) welding, friction welding (which uses friction to generate the heat for welding), and stick welding.

Key characteristics of quality welding that lead to dependable results include a certified welder performing the process according to appropriate welding codes, careful preparation of the weld area, the correct choice of the welding process used, and non-destructive testing of the final weld to ensure that it will hold. Typical welding projects in hydraulic applications include welding the end cap and rod ends into place on hydraulic cylinder systems, welding hydraulic ports, weldable tube fittings, and enclosure fabrication involving sheet metal.

The importance of welds being performed by a certified welder cannot be overemphasized. Knowledge and skill are required for a solid weld, and some materials (such as stainless steel) are more challenging to work with. Since welding is often used in connection with load-bearing parts, it is also important that non-destructive examination (NDE) according to industry-accepted standards is used to verify that the weld will indeed hold. NDE can include but is not limited to visual inspection for surface flaws and defects, radiographic inspection, magnetic particle inspection (for ferrous, magnetic materials), ultrasonic inspection, and liquid penetrant tests.

Conclusion

Custom parts are an excellent option when the OEM and aftermarket suppliers do not have the needed part in stock, or in fact no longer carry it. Custom fabrication also works well when a part only needs to be repaired rather than replaced. In many cases, it can be far more economical to have a basic repair performed on a part that otherwise has significant usable life remaining. Custom manufacturing also allows for parts to be modified for improved performance or reliability. When custom fabrication of repair parts is deemed appropriate, remember that before selecting just any fabrication shop it is critical to make sure that it has the right equipment, a staff that knows how to use it properly, and where applicable, has the proper certifications. This is especially important when it comes to fabricating welded parts whose failure could result in damage to equipment or injury to technicians and operators.

MAC Hydraulics

In addition to offering on-site maintenance, troubleshooting, and repair of hydraulic systems and components, MAC Hydraulics also offers custom fabrication services. From state of the art CNC/CAM milling machines and lathes to more common but no less necessary tools such as drills, lapping stables, and metal cutting saws, our facilities have everything needed to not only fabricate parts from raw materials to reverse-engineering parts that are no longer available. We also have experienced, certified welders who work with materials including stainless steel, carbon steel, and cast iron. Whether you need some small custom valves, a basic repair to a hydraulic cylinder, or manufacturing of a custom manifold that the OEM no longer makes, you can count on MAC hydraulics. Contact us today!