Product Assembly Process in Manufacturing

The assembly process, otherwise called assembly line or production line, is a way of generating a product in which various workers, machines, or equipment sequentially add pieces or materials. It might be a partially automated process because human intervention may be required at any of the process stages. For instance, A may put a new engine in the automobile and ship it to B, who would then fix the doors. Then B hands it over to C, which puts the wheels on it.    

Every worker has a specific task, and unfinished goods are assigned to each worker in turn. Workers can build numerous items at once; for example, instead of putting together one car at a time, they can use their capabilities to put together several vehicles during the day. Meanwhile, companies assess a product and its design using a design for assembly (DFA) technique to establish assembly order and identify concerns that may affect each task. Each task is classified as either manual, robotic, or automatic and allocated to one of the manufacturing plant’s different stations.

For the record, the Ford Motor Company devised this method around the turn of the previous century; it is when automotive mass production began. But remember that the manufacturing and assembly processes should not be intermingled. The actions involved in assembling a finished product from components or partially assembled units are called assembly. In contrast, manufacturing means turning raw or semi-raw materials into a finished product that can be sold.

Different Types of Product Assembly Line Methodologies

There are various ways to have assembly line manufacturing processes, depending on the arrangement, design, stages, production needs, etc. Here are a few examples:  

The Modular Method

It is an advanced assembly line method that increases the efficiency of parallel subassembly lines flowing into the final assembly line to improve throughput. Parallel subassembly lines produce numerous smaller items simultaneously in this process. All lines or more miniature goods are integrated after each assembly line to form the finalized final product. Modular assembly, as applied to automotive manufacturing, would entail assembling various modules – chassis, interior, and body – on separate assembly lines before combining them on a final assembly line.    

Cell Production

Rather than having a separate stage for each essential process, this assembly line method uses machines that can do numerous jobs in a single step. Robots are utilized for materials handling and welding, and cell operators can do three or four tasks at a time. A single operator or a multi-person work cell can run a cell of machines. It is also feasible to link older machines and devices with newer ones in these machine cells, decreasing the money spent on new machinery.

Production as a Team

This method required teams to engage in several phases and even final quality control stages to ensure a high-quality finished product. In other words, where workers would work at one or two workstations and perform dreary and repetitive tasks, worker teams can now follow a job through the assembly line to conclusive quality checks. Supporters hail the team production strategy to increase worker involvement in manufacturing and the system’s knowledge.  

U-Shaped Assembly Line

Instead of a straight production line, a U-shaped or curved assembly line might be used, along with workers standing between the curves. Ultimately, it allows for superb communication throughout the production stages. Assemblers can observe each process, including what is coming next and how quickly it will happen, and one person can accomplish numerous tasks. Changeovers are also more manageable in a U-shaped line, and cross-training is made more accessible. Consequently, the advantages of the U-shaped line have led to an increase in its widespread adoption.

Just-In-Time (JIT) Manufacturing Methods

The just-In-Time manufacturing method was created to lower the expense of carrying an inventory of parts and supplies. In this technique, manufacturing plants keep an inventory of only one day or a few days’ worth. A JIT system relies upon the suppliers to supply components and materials on an “as required” basis. However, future advances in this sector may need suppliers to set up facilities within the manufacturing plant to ensure a more efficient supply of materials and parts.

Pros and Cons of Manufacturing Products with Assembly Line

Here we explore different pros and cons of manufacturing products with an assembly line.


  • Chinese assembly lines create roughly half of all commodities and products worldwide. One of the leading causes that pushed China into industrialization in the first place was mass production. It remains one of the most significant advantages of product assembly.
  • The experts will ensure that you acquire large quantities of your product as quickly as possible. You’ll be able to maintain consistent production and restocking strategies this way. The more stuff you have on hand, the more likely you will make sales. Assembly lines will save you money in the long run while improving your sales and profits.
  • If you make your product by yourself or with a small group, you can’t ensure each item will be identical. However, with an assembly line, you can bet on consistency, saving you the headache from frantic customer calls grumbling about the product’s aesthetic condition.
  • Manufacturing teams are always experimenting with new technologies and materials to enhance efficiency. The procedure improves with each upgrade.
  • Products will be of the highest grade and quality. Quality inspectors positioned at the end of the assembly process inspect the final product for defects and non-conformities.


  • Assembly lines provide workers with monotonous jobs. Hence, locating people who desire to work this job for eight hours or longer isn’t easy. People who work in product assembly stand in one location all day and perform one task, such as making sure a machine screws a top on the right. Many people might also suffer terrible injuries and maiming.
  • You’ll need to invest a massive sum of money to start your product assembly business. Start-up costs, human labor, and industrial space should be factored into the budget.
  • You’ll need to consider things like the materials you’ll utilize for your product. It would be best if you also examined the procedures used by the team and the assembly line’s shape. Some people may favor a U-shaped line as an example since it increases manufacturing efficiency. Accordingly, a great deal of strategic thought is necessary.

A Relevant Concept: Design for Assembly (DFA)

Both “design for manufacturing and assembly” (DFMA) and “design for assembly” (DFA) refer to a set of methodologies for matching the conceptual and design phases of product development to the appropriate manufacturing method, assuring ease of production and cost-effectiveness.

Design for assembly makes the assembly process simpler, faster, and more uniform, all of which have favorable productivity implications and help manufacturers stay relevant to meet customers’ demands. DFA techniques emphasize minimizing part count and assembly processes while also ensuring that the assembly process is as error-proof and cost-efficient as feasible.

It is a fact that the main objective of DFA is to minimize the assembly costs of products and parts. Nevertheless, its implementation in product design has likewise improved product quality and durability and reduced inventory of parts and production equipment.

Design For Assembly (DFA) Rules

  • The most obvious is to employ as few components as feasible.
  • Assembling a product with traditional fasteners can take up to 50% longer. Fasteners can be eliminated from objects by incorporating them directly into pieces.
  • While it may not be possible to disregard fasteners entirely, at the very least, you can utilize the same type of fasteners throughout the product. This is true not only for a single object or product but also for common parts throughout the entire product range.
  • You should think modular. Indeed, making a modular design implies effortless assembly for a manufacturer. Similarly, disassembling components shouldn’t be a riddle, and there should be only one understandable method to disassemble components.
  • Components and products may be manufactured worldwide and have to be shipped. Therefore, you should ensure they’ll be convenient to pack and ship.

Significance of Assembly Design

  • Design optimization is provided by DFA, which eliminates design revisions and alterations. Thus, it avoids production delays, enabling the rapid development of new products.
  • DFA ensures superior product designs at a lower price. This is because it uses fewer pieces in product design and produces less waste of production materials thanks to reduced trials.
  • Design for assembly ensures more dependable products by minimizing the number of assembly pieces and lowering the risk of failure.
  • While the assembly design seeks to make assembly more manageable, it also makes disassembly more straightforward and ensures product maintenance and repair.
  • Because machines or robots align the assembly elements, the design for assembly allows for automation in production processes. This self-aligning gives rapid and easy production.

DFA vs. DFD vs. DFM

Due to the growing relevance of longer-lasting products, recycling, and reusing, both DFA and DFD have garnered much attention in recent years. Both of these ideas have similar goals, and they are cost-effective. The focus of design for disassembly (DFD) is on the afterlife, recycling, and reuse. DFD can be utilized in a variety of items, including electronics and a design method for housing and construction. In contrast, design for assembly is applied on a smaller scale for small-sized products and objects and focuses primarily on part reduction.

Design for Manufacturing (DFM) is similar; the primary distinction is that DFM focuses on choosing cost-efficient features, materials, and parts. DFA and DFM are two distinct concepts that, in recent years, have merged to form a single philosophy known as Design for Manufacturing and Assembly (DFMA). This process focuses on simplifying an object’s design to make its manufacturing efficient and straightforward. As a result, DFM and DFA operate differently.

Applications for DFA

Design for manufacturing and assembly applications can be found in various consumer product design fields. In the same way, it is extensively utilized in sectors that need a high demand for goods while also maintaining high quality and productivity.

E.g., some businesses seek to lower their production costs, while others want to increase their output without hiring more labor. Another company’s goal may be to simplify and improve the reliability of its product. Design for assembly is applicable in their production processes and ensures their preferred results, regardless of the different demands of these companies.

When And How To Choose A Product Assembly Partner?

Scaling up production or launching a new product line are two examples of how you might put an assembly team’s skills to work for you. Nevertheless, it’s critical to locate a partner who shares your high standards and provides top-notch assembly services. Also, you must seek an assembly partner that provides testing services to ensure the completed components or products meet your quality requirements. In this regard, we take on assembly jobs regularly. Our entire staff is dedicated to providing you with the best, on-time, and affordable product assembly services.

Tips for Choosing Your Product Assembly Partner

When choosing a product assembly partner, some of the issues you should be concerned about are:

  • Facilities – Are the facilities adequate for your task? Do they have the necessary equipment to deliver what precisely you’re looking for?
  • Experience – Since start-up contract manufacturers have a history of closing in the middle of jobs, their time in business coupled with financial stability is a crucial consideration.
  • Quality Control (QC) – Does the company have a quality control system in place? What methods of visual and non-destructive testing (NDT) do they use? What assurances do you have that the raw materials you require will not be replaced with lower-quality materials? Moreover, are you allowed to come in and inspect at any time?
  • Methods – Preferably, you will want a company that employs lean manufacturing procedures, conserves resources, and operates in an environmentally sustainable manner.
  • Price – Is the price significantly greater or cheaper than that of competitors? Please remember that a low quote could imply that low-quality materials and unapproved shortcuts were employed during the manufacturing process.
  • On-time delivery – Can your product assembly partner provide evidence that they meet deadlines? Are you able to investigate the delivery metrics?