What is Mechanical/Electromechanical Assembly?

Learn Up: Precision Mechanical and Electromechanical Assembly

Buyers at Original Equipment Manufacturers (O.E.M.s) regularly source custom mechanical parts and components as standalone affairs. Once the parts are received, they are then assembled in-house with other parts to make a functioning product that, once packaged, becomes a finished good ready for distribution. However, there is a better way!

Did you know that you can streamline your sourcing and assembly with suppliers such as Prismier? We not only manufacture the subcomponents, but we provide the value add of integrating both subassemblies and complete final assemblies. Read on to learn about the many advantages of this arrangement.

Boxed in

Electromechanical assemblies likely require joining through welding or adhesive bonding, or the use of nuts, screws and washers, or insertable hardware known as PEM fasteners. They often contain printed circuit boards (PCBs) and cables, as well as heatsinks, bearings, fans, and other components. Some of these are custom orders or require special software to function, while others are standard items, ready for purchase.

When completed, such products perform a variety of everyday functions. The power supply in a desktop computer is an excellent example, as is the computer itself, but countless other electromechanical assemblies exist. These range from the internal workings of the cash machine you stopped at on the way to work, the control panel on the tractor you drove all day, or the automatic garage door opener that lets you in each night.

Most of these are known as box build assemblies, although other non-orthogonal assemblies are certainly possible. From the mechanical side, these are often referred to as enclosures, housings, chassis, or weldments. Regardless, these clever contraptions usually begin life in one of the following ways:

• A flat sheet of aluminum or mild steel that’s either cut to shape on a laser-cutter then bent into the desired shape on a semi-automated press brake or knocked out in a single stroke on a stamping press. See our blogs “What is Fabricating? Part I”, “What is Fabricating? Part II” and “What is Stamping?” for more.
• A plastic resin which is melted and injection molded into shape. Refer to our blogs “What is Plastic Injection Molding?” and “What is Rapid Injection Molding?” for a thorough comparison of these processes.
• A non-ferrous metal which is die cast into a mold and cured under pressure. Refer to our blog, “What is Die Casting” for more details.
• Metal or plastic plate or bar stock or rod which is milled or turned via the subtractive process of CNC machining. See our blogs “What is Machining? Part I” and “What is Machining? Part II” for more information.
• A plastic or metal in any of a wide variety of forms including resins, filaments, and powders which are used in any number of additive processes to grow 3D printed parts, usually in lower volume situations. Refer to our blog “What is 3D Printing?” for a look at the many options with this technology.

Any of these parts could then be sent to the powder coating or painting line for finishing. From there, the completed housing heads to the assembly department.

As mentioned, a variety of electronic and mechanical components might be attached here, hence the name “electromechanical assembly.” Fans and covers are often screwed into place. Bearings are pressed onto rotating shafts. LED lights and switches become connected to power supplies, while wheels, brackets, and locking mechanisms get installed and adjusted. It’s a long list, and again, not all electromechanical assemblies are boxy in nature, although these certainly represent a big chunk of it.

Joining forces

For those looking to purchase completed assemblies and subassemblies rather than discrete parts—and there are some excellent reasons to do so, which we’ll get to in a moment—here are some of the more common operations you’ll see performed in an assembly department like Prismier’s, as well as some things to consider when looking for a supplier:

• Fun with fasteners

  
  This one’s pretty basic. When sheet metal, machined, die cast or plastic parts come together, threaded fasteners (PEM or other varieties) are usually the first choice for the designers of such parts. That’s because they’re well-understood (the fasteners that is, if not the design people), are readily available, and inexpensive. That, and it’s easy to disassemble something that uses nuts and bolts. In lieu of fasteners, in some applications, holes will be tapped providing a means for you to screw into, as described above. Rivets are another great option although they are a more permanent attachment method.

• Sticky fingers

  
  Many grade school kids learn early on that Elmer’s glue A) tastes good, and B) is pretty good at sticking things together. Still, a more grown-up, permanent approach is to use liquid adhesives or pressure-sensitive adhesives, or PSAs. Though not very tasty, they are extremely effective at joining both metals and polymer. They’re also quite weather and corrosion-resistant, and easy to apply, which reduces assembly costs. That said, it’s important to use the correct amount, which is why Prismier’s assembly department has pneumatic dispensing machines, just as they have DC torque tools for very precise tightening of threaded fasteners.

• Wonderful welding

  
  Welding is another more permanent attachment method with several varieties. Seam welding is often used on a box or enclosure. Additional assembly methods include MIG, TIG, or spot welding. Spot welding is a quick method similar to riveting where metal is fused together. In the case of plastic, ultrasonic welding would be used.

• Beyond housing

  
  Your mechanical supplier should always work with you in regards to complete BOM check and assembly. If there’s a need for custom plastic injection-molded parts such as snap fits, bezels, or standoffs, they should be well-equipped to both manufacture and incorporate them into your assembled product. For standard catalog items such as fans, batteries, switches, and even more sophisticated components like Raspberry Pi computers or lighting strips, the supplier should take care of ordering and installing them.

  They should also be happy to apply any labels, stickers, or artwork that accompany the final assembly in addition to any other mechanical items to be assembled including latches, handles, locks, and gaskets. In many cases your mechanical supplier will also install the PCBs and wiring harnesses mentioned earlier, although they will likely prefer to work with your preferred suppliers.

• Size matters

  
  What kind of assemblies are we talking about here? Let’s just say products as small as a matchbook to those the size of a pickup truck, each containing dozens of subassemblies of anywhere from simple 2-part assemblies to those that go into the thousands of individual components. Some of these are the box builds discussed a few paragraphs ago, but practically any type of mechanical or electromechanical assembly is fair game here. Consumer products, advanced machinery, industrial hardware, gaming kiosks and charging stations and medical test devices…the list goes on. Most of these begin as prototypes, go through the PPAP phase and ramp up to full production.

The buck stops here

As stated a few paragraphs back, there are some excellent reasons to outsource this assembly work. For starters, such vertical integration means that the company that performs the manufacturing work, whether sheet metal fabrication, machining, die casting, stamping or molding, is also the one doing the final assembly. Lead-times are shorter, costs go down, and there are no last-minute surprises when parts purchased from two different suppliers don’t mate up as they should. If something doesn’t fit when it gets there, it’s not your problem, the supplier will have to sort it out. Products arrive at your facility packaged and ready to go or, if you prefer, they can be shipped to any of your distribution centers worldwide, streamlining operations even further.

Take that one step further. Suppliers like Prismier provide value added services such as VMI (vendor-managed inventory). kitting services, and enhanced packaging solutions to save you time and money. From kitting and bar coding to custom crating and boxing, the supplier can have everything ready to ship to your end consumer—right down to inserting an instruction manual. Single-sourcing of these kits and assembled products significantly shortens the supply chain. Eliminate extra steps between you and your customer by allowing the supplier to handle your complete packaging needs.

Aside from using CNC machinery and advanced software systems to design, manufacture, and assemble a huge variety of products, at Prismier we also practice Lean Manufacturing principles such as Kan-Ban, 5S, SMED, and continuous or “single-piece” flow, all key concepts of the Toyota Production System.

As its name implies, continuous flow manufacturing moves parts from one operation in small batches—often just one or two pieces—rather than completing all of Op. 10 on a job before moving on to Op 20. Work-in-process is thus greatly reduced, and if a defect is found (it happens to the best of us), only that batch of parts is affected. Best of all, customers can expect to receive their parts or assemblies much sooner than they otherwise would, at the best price possible. At Prismier we call it Manufacturing Simplified.