INTRODUCTION TO MANUFACTURING PROCESSES-OVERVIEW

Audio: Introduction to manufacturing processes-overview

As a mechanical design engineer, you must have various skills to turn your design intent into a reality. Amongst numerous other things, you should be familiarized with different manufacturing processes and, most importantly, how to optimize your design to fit those processes. In the introduction to the manufacturing processes article series, we will investigate the different techniques we can use to get the desired final geometry.

The first goal is to look into the various manufacturing processes and learn the basics. The second goal is to have an overview, or a list, of different processes we can use. Lastly, the goal is to create a strong foundation for further detailed investigation into the processes and look into the so-called design for X (DFM – design for manufacturing, DFA – design for assembly, DFQ – design for quality, DFC – design for cost, etc.).

Introduction

Mechanical design engineers involved in the new product design have one main goal: to provide customers a finished product according to the customer’s specifications with satisfactory quality and price. In the process, a company needs to profit from it. Of course, the challenge always lies in the quality/cost realm. It is not always that the lower price means lower quality and vice versa. There is a fine line between the two, and the mechanical design engineer is responsible for finding it.

There is a big misconception among mechanical design engineers that the responsibility for the manufacturing and assembly process lies with the manufacturing engineers. That is only the truth when we are talking about ramping-up production. But the design phase comes before the ramp-up. During the design phase, most of the processes are defined, and afterward, manufacturing engineers must clean up your mess and figure out how to scale up production based on your design. That is why mechanical design engineers must be deeply familiarized with the manufacturing and assembly processes

The mechanical design engineer must implement optimal quality and cost in design. The further down the line we make changes to our design, the higher the related costs, which leads to the unnecessary increase in the price, delays, and lower the company’s profit. Even without the properly defined processes inside of the company, and if you do not know what DFM and DFA stand for, there is one thing that you can implement in your day-to-day work that will yield tremendous results. It is called being a decent human being. Let me elaborate.

If you have been reading my articles, you know that I like to offer a different perspective on mechanical design engineers and our vocation. I am trying to give you different perspectives, and I hope some of them will stick with you. Most people think that their job or department is the most important in the company. When a new product is developed, they are the key person in the whole project. That is rarely the case. What actually is the case is that every department in the company is equally important to the company’s success. There is no room for “being better or more important.”

The reason why I am mentioning this is that I met a lot of mechanical design engineers that did not play well with others. For example, I witnessed a mechanical design engineer design a product and create a drawing, and the manufacturing department would receive the finished specification. Basically, saying take it and make it. That approach hurts you more than other departments and is absolutely wrong.

As a mechanical design engineer, you must have a wide range of skills. However, you still do not spend the whole day working in production, machining and assembling different components. But people in production do. They are involved in the art of making things every day, the whole day, probably for many years. These people have tremendous experience and insight into the process, and their contributions can be extremely useful. There is no place for your ego at your job; you are only damaging and denying yourself from learning from their’s experience.

Instead of going solo, try the following scenario. Next time when you are working on assembly for your production, when you are done with the design, create a basic version of a drawing and go to your production. Talk with the people that should assemble it every day. Swing by the manufacturing engineering, asking for their input. There will always be good and bad suggestions; just filter through them and use the good ones. The bad ones, however, could trigger you to get other better ideas. Remember that you will maybe build a few assemblies, but people in production may do it for thousand and thousand. So make it easier for them.

If you need to send a component to an external supplier, talk with the people who are responsible for suppliers. Ask them about their opinion on which suppliers you should involve. Furthermore, speak with your supplier, and ask him if there is something you could do to increase the quality and reduce the cost of the components. Involve people in the design process, and use their knowledge and experience to improve your design.

It is good to know what people think about and what they may do with the assembly, something that you may not think humans would ever try to do. Furthermore, it gives people a feeling of being valued and a feeling of shared responsibility for the product you are developing. The best way would be to involve all these people during your design process and get their input as early as possible. In Croatia, we say: “two heads are always smarter than one.”

In addition to being a normal person, various techniques can be used to ensure we choose the proper manufacturing process. With correctly implemented procedures and design processes inside the company, we can ensure that our products are designed with quality and cost in mind. But first, we have to get familiarized with the term “manufacturing” and basic manufacturing processes, and then we can dig deeper into the individual process and how to improve our design.

What is manufacturing?

In simple words, manufacturing is the process of making products. Different manufactured products can be used to make other products. In this context, individual parts, like bolts, nuts, pins, gears, etc., are called discrete products. On the other hand, products like a roll of aluminum foil, wire, metal pipes, different material sheets, etc., that are used to cut into individual pieces of various lengths for specific purposes are called continuous products.

In a deeper context, manufacturing is the application of physical and chemical processes to a given starting material, with the goal of altering geometry, properties, and appearance to add value to the starting material. The result is a part or a product with a higher value than starting material itself. The product can be a single part or an assembly of multiple parts; manufacturing is concerned with both.

Not every company can produce everything; all of them have limited capabilities. Manufacturing capability is defined as a manufacturing company’s technical and physical limitations. These limitations are the reason why many companies are collaborating with other external companies to increase their manufacturing capacities.

Do not be surprised as a mechanical design engineer that you collaborate with different suppliers in order to get the parts you need for your product. For example, if you need a standard ISO bolt, your company will not manufacture it, but instead, you will purchase it from the company that the bolt is a standard part of their portfolio.

Or let us say that you want to create a prototype of your product. You could source it out to a 3D printing company, and they could make it for you. Or, you could order a 3D printer from a 3D printer manufacturing company and purchase filament from them. Whatever you decide to do is completely fine, but your company will surely not invest millions and millions of euros to have a 3D printer produced in-house from start to finish.

Production quantity is defined as the number of units produced annually.

We can divide the production quantities into the following categories:

Low production – 1 to 1000 units per year
Medium production – 1000 to 10 000 units per year
High production – 10 000+ units per year.

The production quantity is essential information. Depending on the annual quantity product sale forecast, we will choose the appropriate manufacturing process, which significantly impacts the final product cost. Therefore, mistakes in the estimates can have a significant economic impact on the company.

Manufacturing processes classification

There are many manufacturing processes available, and we are not going to mention each one of them. However, we will note many of them, and with time we will process lots of them and give you the best insight possible. Please be patient with me, there are a lot of different processes, and it will take some time to process them all. Below you can find the list of various manufacturing processes and links to relevant articles.

We can divide manufacturing processes into processing and assembly operations.

Processing manufacturing operations

Processing operations can be further divided into material shaping processes and property enhancing and surface processing operations. Material shaping processes alter the geometry, property enhancement improves the physical properties, and surface processing operations improve the surface condition of starting material.

Shaping manufacturing processes

Material removal (machining)

Turning and boring – overview
Milling – overview
Drilling – overview
Thread cutting – overview
Shaping and planing – overview
Broaching – overview
Grinding – overview
Honing – overview
Lapping – overview
Chemical machining – overview
Electrochemical machining – overview
Electrical discharge machining – overview
Sawing – overview
Laser beam machining – overview
Electron beam machining – overview
Plasma arc machining – overview
Water jet machining – overview
Abrasive jet machining – overview

Deformation processes (forming)

Sheet-metal forming
Vacuum forming
Blow molding
Superplastic forming
Forging
Rolling
Extrusion
Drawing
Slip casting
Pressing and sintering
Isostatic pressing

Solidification processes

Injection molding
Rotational molding
Compression molding
Reaction injection molding
Continuous casting
Gravity die casting
Pressure die casting
Centrifugal casting
Sand casting
Squeeze casting
Shell molding
Investment Casting

Rapid prototyping (liquid, powder, and solid form)

Stereolithography (SLA)
Solid Ground Curing (SGC)
Solid Object Ultraviolet Laser Plotter (SOUP)
Jetted Photopolymer System (JPS)
Three-Dimensional Printing (3DP)
Selective Laser Sintering (SLS)
Direct Metal Laser Sintering (DMLS)
Laminated Object Manufacture (LOM)
Fused Deposition Modeling (FDM)
Thermal Phase Change Inkjet Printing

Property enhancing and surface processing operations

Softening (Annealing/Tempering)
Hardening (Ageing, Full quench, Step quench)
Stabilizing (Freezing, Normalizing, Stress relieving)
Cladding
Electrochemical
Hot dip
Thermal sprayed
Weld coatings
Vapor deposition
Mechanical shot peeing
Passivation
Diffusion

Assembly operations

Assembly operations involve joining two or more components. There are different assembly systems: manual, flexible, and dedicated systems. Usually, these systems are a combination of the following assembly operations:

Permanent joining processes

Welding

Friction welding
Explosive welding
Ultrasonic welding
Gas welding
Seam welding
Spot welding
Metal inert gas welding
Tungsten inert gas welding
Manual metal arc welding
Plasma arc welding
Laser beam welding
Electron beam welding
Thermoplastic welding

Adhesive bonding

Anaerobic
Emulsion
Epoxy resin
Hot melt
Polyurethane
Tape
Toughened adhesive
Polyimide

Soldering and brazing

Gas soldering
Furnace soldering
Induction soldering
Resistance soldering
Dip soldering
Iron soldering
Gas brazing
Induction brazing
Resistance brazing
Dip brazing

Mechanical fastening manufacturing processes

Non-permanent

Tappered keys
Threaded fasteners
Pins
Anchor bolt
Threaded inserts

Semi-permanent

Shrink/expansion fit
Press fit
Blind rivet

Permanent

Riveting
Flanging
Staking
Seaming

Closing words

During my career, I had a chance to witness numerous ideas becoming a reality. I made prototypes with my own hands and designed products that ended up on my desk. As a mechanical design engineer, this is the greatest satisfaction I could get. Seeing your idea develop from an electrical impulse in your brain to the physical entity in your hands is the best part about being a mechanical engineer. However, to do that effectively and economically, a wide range of skills are required.

Usually, we design products that are either extremely expensive or are produced in high quantities or both. In any case, the costs involved are high, and we are expected to deliver products with appropriate quality and costs. For that reason, you have to be deeply familiarized with manufacturing processes. The better you understand it, the better your design will be.

There are various techniques you can implement in your design process to ensure that your design will fulfill all requirements. Still, as I said previously, the most important one is to talk to and involve other people in your design.

This article is intended as a general overview and guide where you can find all relevant links to the different manufacturing processes. I will keep working on expanding the list.

Now you have a broad overview of some manufacturing processes you could use as a mechanical design engineer. However, I suggest you go through the text once more and identify areas you think need more understanding and clarity. Then, once you have identified those areas, start building up your knowledge in those areas.

To make it easier for you to find related posts, check the “Further reading” chapter below. Do you have any questions or need something to be clarified better? Leave a comment below, and I will give my best to adjust the post accordingly.

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