7 Tips for Reducing Sheet Metal Fabrication Costs
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7 Tips for Reducing Sheet Metal Fabrication Costs
Sheet metal fabrication is a popular prototyping and production process. It involves the use of different techniques to turn flat metal sheets into the desired geometries and parts. Some standout features of sheet metal is that it is highly durable and very versatile.
To produce the final products, sheet metal undergoes different processes such as cutting, bending, punching, joining, and finishing procedures. However, each of these manufacturing processes adds to the cost of sheet metal fabrication. Further, the cost of raw materials can quickly add up. It, therefore, becomes important to implement a cost-saving plan and reduce sheet metal cost. Since sheet metal fabrication can be a labor-intensive process, a crucial aspect of minimizing costs is reducing the number of operations the fabricator needs to perform to form the desired component.
In this article, I have compiled useful and practical tips to help you save on your metal fabrication project while maintaining the quality of your product. But first, I’ll guide you through estimating costs for sheet metal parts.
How to calculate the cost of sheet metal parts？
Before we get into the tips and insights that can help you lower sheet metal fabrication costs, it’s important to understand the cost composition of sheet metal parts. When you know the cost structure of a part, it becomes easier to optimize the production process and choose the right pricing strategy.
Sheet metal fabrication consists of numerous processes. To form a functional part from the raw material manufacturers will use operations such as drawing, cutting, bending, shearing, notching, laser cutting, assembling, and painting. Each of these steps in the production cycle adds to the cost of the sheet metal part.
I’ll share helpful concepts and ideas to help you calculate the cost of single or multiple sheet metal parts.
Step 1: Break Down the Production Cycle
The production cycles of varying products are usually different. Also, product development often involves multiple steps or phases. To estimate the cost of sheet metal parts, you need to break down the production cycle into simpler phases.
For example, you may be using raw material A and B in machine 1 to produce output 1. You may then combine output 1 with raw material C in machine 2 to generate output 2. In this case, you can calculate the cost incurred in machine 1 before moving on to machine 2.
It’s essential that you divide the production cycle into separate phases. This allows you to focus on a single process at a time.
Step 2: Compute the Cost of Raw Materials
Raw materials are an essential component of any production process. Depending on your desired product, you may use one or multiple raw materials. For example, automobiles require a variety of raw materials including steel, plastics, rubber, and special fibers.
To estimate the cost of raw materials, you’ll need to calculate the quantity of raw materials that go into making a single product.
- The cost of raw material = Volume x Material Density x Material Cost per Kg
For example, let’s say a plate has a length of 650mm, width of 450mm and a thickness of 1mm. If the cost of the material is $0.8 per kg and it’s density is 8.0 kg/dm3, we’d obtain;
- Raw Material Cost = (6.5 x 4.5 x 0.01) x 8 x 0.8
- Raw Material Cost = $1.87
You’ll repeat these steps to calculate the raw material cost for all materials used in production.
Step 3: Calculate Machining Cost
To calculate the machining cost, we need to have the following information;
Hourly cost of the machine
Cycle time (how long it takes to machine a single part)
Efficiency of the setup
You can compute the machining cost as follows;
- Cost of machining = (Hourly machining cost x Cycle time)/ Efficiency
As an example, let’s say the hourly cost of a machine is $90. If the system has an efficiency of 85% and the cycle time is 12 seconds, we’d get:
- Machining cost = (90 x 12)/ (0.85 x 3600)
- Machining cost = $0.35
At this point, the total product cost is the sum of the raw materials cost and the machining cost.
- Total Product Cost = Raw Material Cost + Machining cost
- Total Product Cost = $1.87 + $0.35 = $2.22
In our example, the cost of raw materials accounts for 84% of the total product cost while machining cost contributes the remaining 16%. Therefore, reducing the cost of raw materials (by minimizing the amount of scrap) would result in significant savings.
Step 4: Repeat These Calculations For The Different Product Development Phases
As I previously mentioned, the production cycle of a product often consists of numerous phases. From the above calculations, we’ve computed the production cost in phase/ machine 1. To come up with the total cost of the part, you’d need to repeat these calculations for phase 2, phase 3, and so forth up until delivery.
Tips for Reducing Sheet Metal Fabrication Costs
Now that you’re familiar with how to calculate the cost of a sheet metal product, I’ll take you through cost-effective sheet metal fabrication. These tips will help you manufacture high-quality sheet metal products at affordable prices.
#1. Design for Manufacturability (DFM):
Complex designs with intricate features and geometries are expensive to manufacture. The opposite is also true. Simpler designs are usually more affordable.
There is no denying that complicated designs with specialized design elements can be intriguing. However, they typically require numerous cuts, bends, and welds and this adds to the cost of production.
Therefore, it’s best practice to stick to simpler designs if you’re trying to eliminate extra costs. This also means avoiding features such as machined pockets, chamfered edges, and blind holes when possible. These features significantly increase machining costs and lead times.
Also, if your design includes punch-form features such as ribs and bridge lances, opting for standard sizes is a simple way to cut costs. With non-standard sizes, it may mean using special tools which adds to the cost and lead time.
#2. Material Selection:
The cost of materials directly adds to sheet metal fabrication costs. Therefore, making smart decisions when it comes to raw materials for your project can help you significantly cut costs. Here are some practical and actionable tips that I’d recommend to help you save on material costs.
During the prototyping phase, its advisable to opt for a cheaper material. For example, your fabricator can produce aluminum prototypes rather than stainless steel.
When it comes to the actual manufacture of your product, you want to opt for an affordable raw material that is still capable of performing the intended function.
Aluminium, steel, and stainless steel are some of the most common sheet metals. Therefore, if you choose to use these materials, you can easily obtain them from the manufacturer without incurring a special order fee.
Fabricators who buy materials directly from mills can help you negotiate better deals. Due to their existing relationships and experience with mills they can help you secure lower bulk pricing. Also, these fabricators may be able to advise you on cost-efficient shipping and storing solutions.
Where possible, opt for common rather than specialty finishes. Finishing processes such as anodizing, chromate plating, and powder coating are common and readily available and this makes them affordable. Specialty finishes increase both time and production cost.
#3. Using upgraded and modern fabrication tools:
Expert fabricators will have the right updated tools to successfully execute your project. Infact, you can request for a tour of the facilities to ensure that you’re working with a qualified fabrication company.
Advanced tools and modern technology allows fabricators to produce highly precise products and eliminate costly errors. The production process is also more efficient and generally faster.
If you are a fabrication company, it’s beneficial to ensure that you’re using up-to-date equipment. Of course, upgrading your machinery would be an expense. However, think of it as an investment that will help you improve productivity, product quality, and drive down costs in the long run.
#4. Limit Tight Tolerances:
It may seem like a good idea to have tight tolerances on all dimensions and surfaces of your sheet metal product. However, this is simply not the case especially if you’re keen on minimizing costs.
Tight tolerances mean more machining time and this directly increases production costs. Common tolerance callouts include distances, radii, and hole diameters.
So, what should you do instead? To reduce costs, assign tight tolerances only to surfaces that are crucial to the function of your product. Not every feature is integral to the functionality of a part. This means that you can apply looser tolerances to some features without compromising the applications or appearance of your product. Loose tolerances allow the machine shop to use low-cost production methods and manufacture parts at a faster rate.
#5. Simplify Your Folds
In sheet metal fabrication, complex parts mean an expensive manufacturing process. To lower costs, ensure that angled bends have a radius that is equal to or greater than the thickness of the sheet.
A small bend on a thicker material would not only be hard to execute but also costly to fabricate. A good rule of thumb when designing sheet metal parts is to opt for the simplest design that will be the most cost-efficient.
#6. Maintain Uniform Bend Orientation
While fabrication technology is now more advanced than ever, it still has some shortcomings. As I’ve already mentioned, one of the simplest ways to mitigate these limitations is to opt for simpler designs whenever possible.
This principle applies to a range of features including angle bends. You can save on production costs by ensuring bends are in the same direction. In other words, avoid designing bends that are oriented in different directions.
When bends are in different directions, the machine operator will need to reorient the sheet metal before machining every bend. This slows down the manufacturing process and increases labor costs. Contrarily, unidirectional bends can be machined without reorientation.
Also, consider using the optimal bend radius when designing sheet metal parts. When the bend radii lies within the ideal range of 0.030 inches and 1x the material thickness, manufacturers can use their standard tooling to form the bend. However, if the specs of the bend radii lie outside this range, the machine shop may need specialized tool sets and this would add to the production cost.
#7. Consider Plating, Welding Costs for Sheet Metal Fabrication
Let’s consider this concept – It’s unsafe to weld pre-plated sheet metal. This because high temperatures on the treated metal cause the release of zinc oxide. This highly harmful compound vaporizes into a gas that is destructive to both people and the environment.
The toxicity of welding pre-plated sheet metal leaves you with one option: use uncoated cold rolled steel sheet. Parts would then be treated afterwards to boost anti-corrosion properties. Hower, there are some glaring downsides to this process – it’s expensive and would significantly increase lead times.
Therefore, your best choice would be to keenly examine your design and determine if it’s possible to completely avoid welding. This allows you to use pre-plated sheets. If joining sheets is essential to your project, you can opt for alternatives such as riveting.
Author
Gavin Leo is a technical writer at Aria with 8 years of experience in Engineering, He proficient in machining characteristics and surface finish process of various materials. and participated in the development of more than 100complex injection molding and CNC machining projects. He is passionate about sharing his knowledge and experience.