Designing mechanical engineering products for low cost and easy manufacturing is a challenging but rewarding task. It requires a balance between functionality, performance, quality, and cost-effectiveness. In this article, you will learn some basic principles and best practices to help you achieve this goal.
The first step is to simplify the design as much as possible. This means reducing the number of parts, features, and dimensions that are not essential for the product's function or value. Simplifying the design can help you save material, time, and money, as well as reduce the complexity and risk of errors. You can use tools such as value engineering, design for assembly, and design for manufacturing to identify and eliminate unnecessary or redundant elements in your design.
Low cost design = highly experience design engineer. Ease of Manufacturing = highly experience design engineer involvement with experience process engineer, production line owner, line leader, operator and production floor to get the manufacturing perspective added inside product design. Maturity of product design = maturity of design engineer
When generating a mechanical design to be cost effective, I believe the most important aspect is understanding how the components will be manufactured. Without a strong understanding of manufacturing processes, how would one begin to understand what is possible? From there you are able to design for manufacture and assembly, reduce part count by combining functionalities and select the most effective means possible to produce the desired quantities.
Apply DFAM principles. 1. less part count 2. part standardization 3. parts symmetry 4. tooling/processing standardization 5. manufacturing easiness/feasibility 6. worker/resource accessibility/skills 7. selection of common materials in-line with SCM stock availability or SCM common demand planning 8. design for logistics The above points not only helps being cost effective material wise but also reduces CT during manufacturing & assembly. The best design is where the assemblers do not waste a second in deciding where or how the part will fit/assemble
I agree with Kenneth Cole on this one. The one issue I have seen in my career is that as a design engineer you have to have an in depth understanding of not only what you are designing but how it is going to be manufactured. The only way to get this experience is to work with the people manufacturing the parts, fabricators, welders, machinists, electrians, assemblers etc. You cannot learn this sitting in front of the computer. I have learned more on the shop floor than I have from any book. You also have to be open minded and not think you have all the answers.
Reduce the time spent assembling the product by relying on integrated fasteners like snaps. Ensure products cannot be incorrectly assembled by implementing good pokayoke procedures. Limit the need to flip or move the product during assembly. Use automation when possible
The second step is to choose the right materials for your product. Materials have a significant impact on the cost and quality of your product, as well as the manufacturing process and environmental factors. You should consider the properties, availability, and price of different materials, and select the ones that meet your requirements and specifications. You should also avoid using exotic or rare materials that are difficult to source or process, unless they are absolutely necessary for your product.
Material's selection needs to be one of the firsts steps when you are design a new product or project. You can't start your product design without explore all materials that can enhance the properties you are looking for in your project. There are thousands of materials and process available and it's worth to explore it.
Design for manufacturability is important , we cannot just design a product that is pleasing to the eye, we should also keep in mind if these product are easily produced, manufactured or can be serviced in a long run if parts needs to be replaced. Additionally, if the product needs to be assembled, we also keep in mind safety of the assembler during the assembly process we also take into consideration the material, we should be able to know what materials are not harmful and best fit to the product based on its usage.
Selecting material is one of the basic and most fundamental things for designing. Designer should look for the environment condition in which they should look for operating temperature, surrounding environment( humidity or expose to other chemicals which leads to corrosion, sunlight (UV rays)) which will impact the material selection. Also material should be selected based on the different standards applicable or needs to follow as per specification or general practice for the design components. Also thinking whether higher grade of same material is required or lower grade will work and last but not least selecting material as per availability in the local market.
Material selection stage offers potential for huge savings and improvements in manufacturability. As with the simplification stage, consider the manufacturing methods available as this will impact the material options. Material cost in product design is not necessarily linear in terms of cost/qty depending on manufacturing methods used, with additive methods generally increasing cost with increased material use and reductive methods reducing costs with increased material. Selecting the optimal material is a balancing act of properties; mass, electrical, mechanical, thermal, appearance and many more. Certain materials can constrain supply chains and manufacturing teams and can cause issues in later product life with legislation restrictions.
I start by looking to see what others may have designed to do the same function. Then see how it can be made better and at a lower cost or improved with simple additions that enhanced features or better quality. Most call this reverse engineering, but it a great way to learn what is already being done. As the old adage goes, "You don't have to reinvent the wheel, but you can improve it."
The third step is to optimize the geometry of your product. Geometry refers to the shape, size, and orientation of your product and its components. Optimizing the geometry can help you improve the performance, functionality, and aesthetics of your product, as well as reduce the manufacturing costs and time. You should use standard shapes and sizes, avoid sharp corners and angles, minimize the surface area and volume, and align the features and components with the manufacturing direction.
Bring in the people who actually have to make it. Machinists and technicians regularly have more experience in this area and may bring in new options. There's also optimization software (topology optimization, generative design) that you can add manufacturing constraints to.
As a plastics injection molding engineer, too often I have seen plastic parts that were designed disregarding basic plastic geometry rules: even wall thicknesses, 60% rib thickness vs. wall, radius inside corners, proper draft, etc. Many part geometries are so complex that they have to bend or break some of the rules, but as more design rules are broken, there is a penalty in cycle time, quality, aesthetics, tooling cost, or part robustness. All of these increase part cost and may even cause failure and redesign after testing or product launch. Having a plastics expert help guide plastic part geometry early in the design stage can save considerable cost, and may even save the entire project.
Product geometry is a critical step during the project design. The engineer needs to take into consideration mechanical and chemical stress, environment, tolerances and process limitations. When geometry is a restriction in your project, sometimes you need to change your manufacture process, based on capability. You also need to avoid some geometries like square edges, sudden section reduction, galvanic pair materials, trying to reduce wear mechanisms or catastrophic failures.
Streamline form for function, beauty, and budget. Seek standardized shapes, smooth curves, minimal material use, and alignment with production flow. A well-optimized geometry leads to a winning product..!!!
Taking into account the manufacturing process when looking at the design can make the manufacturing process cheaper and quicker - if moulding then you can reduce cost of tooling.
The fourth step is to select the appropriate manufacturing process for your product. Manufacturing processes have different advantages and disadvantages in terms of cost, quality, speed, and flexibility. You should choose the process that best suits your product's characteristics, quantity, and market. You should also consider the compatibility, feasibility, and efficiency of the process with your design and materials. Some common manufacturing processes for mechanical engineering products are machining, casting, forging, molding, extrusion, and additive manufacturing.
Always make DFM (Design For Manufacturing) & DFA (Design For Assembly) discussion/ meeting session(s) with stakeholder including your manufacturing engineer and get their feedback. Some parts may need to be produced using other method to satisfy easier assembly process or to have certain feature.
DFM is the foundation stone for any design. Without following this philosophy there is no room for Manufacturing Engineering to improve on productivity & keep set up costs down. As an example: If there are Three individual metal components that are welded together to make a welded assembly, complex tooling/jigs might well be required to generate repeatability from a Quality prospective - This is a set up cost. However is the Design Engineer adopted the Slot & Tab Method of design tooling/jig set up costs are greatly reduced. More manufacturing cells can be added for little investment and more components made to support demand.
Before designing the product we need to understand the manufacturing process and to do this we need to have DFM and DFA discussion or meeting with CFT and take their feedback.
It is really important to be aware of the machines you have available to make the product, their pros/cons and their limitations. Sometimes times,especially for small productions, you may have to make a product in different way for the beginning and for the later production. Consider that from the design as in the future you may be able to invest more in the process to reduce cost per part.
The six step process given here is a good overview but steps 2 - 4 are best consider as three interrelated parts of one step. It is not as linear of a process as suggested. Each affects the other and when considered altogether will result in a better final design.
The fifth step is to test and evaluate the product before and after the manufacturing process. Testing and evaluation can help you verify the functionality, performance, quality, and reliability of your product, as well as identify and correct any defects, errors, or deviations. You should use appropriate methods, tools, and standards to measure and analyze your product's attributes and behavior, such as stress, strain, fatigue, vibration, temperature, pressure, and noise. You should also collect feedback from customers, users, and stakeholders to improve your product.
Prototyping and physical tests like crash test, endurance durability and reliability test requires a huge investments and takes up a significant portion of the R&D budget. A good correlation of the baseline part between the virtual engineering (digital simulations) and the physical testing can eliminate the need for physical testing of further iterations/design modifications and thus decrease the overall cost of the product development.
When testing and evaluating the product, it is crucial to test the design consistency as early as possible using prototyping methods. It is also important to choose the right prototype process for the expected outcome. For plastic parts, going from standard 3D printing like SLA, SLS, or FDM, to CNC machining, to vacuum casting can get closer to the final off-tool behavior of the injection molded part. By leveraging these techniques, we can create prototypes that closely resemble the final product and test the design's correctness and product functionality. By testing and evaluating the product early and often, we can identify any design flaws and make improvements to the product, ultimately improving its quality and reducing costs.
Usually first step before Design will be started is finding proper balance between preliminary SPEC for new product and required cost saving for finding non-optimal features in the SPEC from cost perspectives. Professionally analyzed and corrected SPEC is about 50% of cost reducing effect. Than design of really mandatory parts of Product to be MAX linked to existing technology of manufacturer with exception if some new process can provide significant savings. Proper balancing on all Design' stages is very good way for reaching the real cost optimization.
During the design stages of the product , rapid iteration and testing through the use of CAE tools , digital twins give an idea of how the product will perform under normal and extreme conditions. This can also help save some time , money prior to creating hard tooling .
If the design is carried out correctly and simulation software is used then the risk is reduced but it is important for the end user to test the final product to ensure it meets there requirements. Making sure that the test procedure is representative of the products life is important and also to find methods of accelerating long term performance - (for plastics this is usually increasing the temperature )
The sixth step is to implement continuous improvement for your product. Continuous improvement is a process of constantly monitoring, reviewing, and updating your product to enhance its value and competitiveness. You should use tools such as quality control, quality assurance, lean manufacturing, and six sigma to identify and eliminate waste, variation, and defects in your product and process. You should also seek new opportunities, innovations, and technologies to improve your product's design, materials, geometry, and manufacturing process.
Continuous improvement is about process as much as a specific design. Run After-Action meetings throughout to discuss what went well, what went poorly, what do you wish you had thought of going in. Capture these and try to blend them into best practices for the next iteration or project.
Continuous Improvement lays the foundation for a cost-effective solution for new programs. There is always scope for improvement and making the product as cheap and effective as possible. The lessons learned should be used in the launch phase for the new product development programs right from the concept development phase. Note the amount of scrap, excess lead times and variations in the entire PD cycle. Identify the bottlenecks, the high cost contributors and the efficiency of the cycle Analyze how can a new design be developed which performs all necessary functions with the minimum costs. Try for alternate manufacturing process / material/ change in design / modifying tolerances and improving the process capability
Continuous improvement can be gotten from feedbacks from consumers, complaints received from both internal and external customers, risk mitigation of the product, reusing of waste products or minimizing waste, enhancing the performance and functionality of the product and amongst others.
In the implementation of continuous improvement, I see more than a process; it is a philosophical journey. It is an incessant quest for truth, a constant exploration of how we can surpass ourselves. Tools like quality control and lean production are not just methods but guides that lead us through the narrow path of constant evolution. The pursuit for innovation reflects the intrinsic capacity of the human mind to question and challenge established paradigms, and thus, expand the limits of understanding and experience in a market that is ephemeral in nature.
To design cost-effective, easily manufacturable mechanical products: 1. **Use DFM principles**: Optimize design for simpler manufacturing. 2. **Select materials wisely**: Choose cost-effective, available materials. 3. **Simplify the design**: Minimize part count and use standard components. 4. **Opt for modular design**: Facilitate assembly and maintenance. 5. **Align with manufacturing processes**: Choose processes that match production volume and cost requirements. 6. **Leverage CAD tools**: Utilize software for design optimization. 7. **Minimize tolerances**: Apply only as necessary to reduce costs. 8. **Incorporate feedback**: Use insights from manufacturing and usage to improve design.
Bring manufacturing team into the pre-award of business planning quoting process. Features for manufacturing are pretty much free at this phase of the project. DO NOT let the commercial/sales team make agreements without the engineering teams agreement (no back door deals). Don’t reinvent the wheel, use as much previous program material as possible (where applicable). Get in writing (Maybe worth contracting a court recorded for these meetings) any deviation to the SOR that the customer agrees with. Undocumented agreements are not agreements and you’ll pay to meet that SOR requirement later in in the program. Reassign any VAVE team members to something more productive. Minimize/eliminate changes after SOP+1 year.
In designing for cost sensitivity it's important to understand where the cost is going and ensuring you're getting the ROI on your spend. Looking at areas where long cycle times, waste, scrap and rework are commonly found are the best ways to target design and manufacturing optimizations to lower costs. An example is the use of production consumables (e.g., temporary/added tapes, etc.) in high-volume manufacturing. If such items don't add to the product's function or value, design to avoid them.
Leverage your existing manufacturing core competencies. Risk, cost and time to market could all be reduced if the new design does not require a new manufacturing process.
Use the standard parts as much as possible. This will reduce the design efforts and reduce overall project time and cost. If the part is going to be designed, consider the manufacturing processes that are available in-house, unless otherwise required. This would simplify the redesign over the product's lifespan and reduce costs by avoiding the supplier margin. Tune the design by topology optimization feature in the CAD software. This can effectively show the features contributing to the strength requirements and other features shall be removed to reduce the cost.
When designing it is imperative to be mindful of the manufacturability of the product. That means choosing a material that is cost effective, considering the ease of assembly and disassembly for troubleshooting. This will help mitigate unnecessary waste, minimize parts count, and reduce labor expenses.