If you need to create metal parts then CNC machining & die casting are two broadly used options. These approaches vary in their procedures as well as raw material usage, which impacts the total cost. Engineers and manufacturers usually note that making components with CNC machining have higher material costs in contrast to die casting.
In this blogpost you will know about key factors that drive this cost variation. It also analyzes efficiency, waste and material usage from a global manufacturing perspective.
Analysis of Manufacturing Procedures: CNC Machining and Die Casting
CNC Machining (Subtractive Manufacturing)
In CNC machining the machine eliminates material from a solid block or billet to form the end product. This procedure gives extreme flexibility and precision. However it creates a considerable amount of waste since a large portion of the original material is converted into chips. When costly metals are used then this wasted material greatly increases the total material expense.
Die Casting (Near‐Net Shape Manufacturing)
In simple terms die casting produces components by pouring molten metal into a mold. Only the metal required to fill the mold is used, with a small portion added for sprues & runners. With this procedure companies can produce minimal waste of raw material. Any remaining metal such as gating or sprues can be retrieved and reprocessed to use them again. Consequently die casting gives relatively less material costs per part in large-scale production.
Also See: Forging vs. Casting vs. CNC Machining
Cost Affected by Raw Material Input
CNC machining starts with a raw workpiece that is very large relative to the final component. Manufacturers acquire large‐sized material – such as a steel bar or aluminum billet – so the part can be held & shaped efficiently during machining procedure.
Each & every bit of metal removed during machining is bought at full cost. Suppose half of a billet is cut away then it means that half of material expense for each component is wasted.
In die casting the mass of material used for each part is approximately equal to final weight. The material usage rate in die casting is approximately 90% to 95%. This shows that a very small portion of that material is wasted and most of which can be recovered as well.
Die casting uses high-quantity raw metals, such as molten alloys or ingots which are typically available at a lower price per kg as compared to pre‐shaped workpieces needed for CNC. Depending on specific use machining needs top-notch billet materials that may be high-priced per weight. Conversely die casters can use less expensive alloys or recovered metals.
Keep in mind that some special alloys used for die casting can also be costly. On the other side CNC machining can use a broader variety of materials and some of which are less expensive. However for same material the requirement to acquire additional materials for CNC increases their overall material price.
Comparison of Scrap Handling
Die casting has another benefit in handling scrap. A minimal amount of excess metal, such as gates, runners or sprues, remains connected to components and is cut off. This cutted metal is remelted and used for future casting. This is why negligible amount of material is wasted in die casting. It helps decrease material expenses.
Conversely CNC machining creates swarf and chips that cannot be recycled by the same procedure. Shops retrieve and resell these metal shavings but the price they receive is quite low. Recyclers have to reprocess the scrap so manufacturers pay for material that is never used in the final product. Because CNC scrap cannot be reused in‐house, the price of usable materials for machined components is quite high.
From an environmental point‐of‐view die casting’s low waste improves its status as an environmentally friendly procedure. CNC machining produces more waste that companies have to handle via recycling or disposal, which leads to additional expenses.
Differences in Material Usage and Waste
CNC machining has subtractive nature that cuts away material from workpiece, so it uses a smaller portion of original material. Most of starting block is converted into machining debris instead of finished part. For instance when a metal block is cutted into a part then a notable portion of block’s mass is machined off and wasted.
Die casting is a near-net shape procedure that operates differently. It makes components closer to their finished shape and uses nearly exact amount of material as the finished component which produces very little waste material.
For this reason CNC machining typically needs more material to be bought for each component. This procedure creates more waste products. This is why it increases cost of material. Moreover it is confirmed by research that CNC’s machining produces substantial scrap which raises costs specifically with costly materials. While die casting creates far less waste metal and processes the metal more sustainably.
Volume-Cost Analysis
In CNC machining manufacturing volume plays a large role in high unit material cost of a component. Engineers usually choose CNC machining for small quantities or prototypes, even though it creates more waste. This is because the initial high cost of a die casting mold is not reasonable for small quantities.
With number of components increasing, the material waste from CNC machining also increases with them. Every part that is machined also contains expense of removed metal so when thousands of components are made then total loss in the form of scrap becomes quite large.
At that point the die casting became a better option. The starting tooling cost is distributed over several parts, and each part uses the material very optimally. In large‐scale production die casting gets a comparatively less material cost per unit. This cost‐effectiveness is key reason behind why large‐scale die casting gives a much lower cost per part.
When it comes to the manufacturing of millions of parts then the difference becomes even more visible. Die casting uses only as much material as is necessary for each & every part, whereas CNC machining wastes 2 or 3 times that much.
Role of Geometry in Costs Differences
The geometry of a part can further increase material price difference between die casting and CNC machining. Creating hollow or complex shapes through CNC machining usually results in uneconomical use of material.
When a component has geometrical characteristics such as deep pockets, internal voids or thin walls then CNC machining begins with a solid block. The machine eliminates material to make these hollow spaces which creates a lot of metal chips as waste.
Die casting operates differently. It creates internal voids, thin walls and detailed shapes by feeding metal into a mold. The mold inherently has voids which are created by the cores.
Casting precisely forms the shape of part so there is almost no need to cut away additional material. For instance a hollow part having complex internal geometries is cast close to its desired shape. Machining the matching part would need removing considerable metal, much of which would be converted to scrap.
Don’t Forget: if a required design needs to remove a significant amount of material and also produces substantial amounts of waste on CNC machining then it is a perfect fit for die casting. If you pick die casting for these shapes then it will help manufacturers to prevent significant amounts of material waste and also decrease cost associated with CNC machining as well.
Ecological Impact on Material Cost
Cost of material is not restricted to only price tag. Resource efficiency as well as eco-related impacts also have a crucial role for several multinational industries. When material is wasted then extra resources and energy are needed to create, transport as well as recycle it. Because die casting uses materials more sustainably, it provides both environmental advantages and cost savings.
If the metal is not converted into chips then less scrap has to be managed and ultimately less energy is needed for re‐melting. CNC machining produces more scrap so there is more built‐in energy in each finished component. CNC machining is less sustainable, unless industries recycle this waste effectively.
Companies must also pay to recycle and manage their scrap that was created from CNC machining. They have to process cutting fluids as well. These additional steps increase total material cost of machining.
How Material Choice Affects Production Cost?
The types of materials that you use in each procedure impact cost of material. CNC machining can operate with nearly all types of material. Engineers can pick from a variety of plastics, metals as well as composites. This range lets them select more available or less priced raw materials as required.
Die casting on the other hand is restricted to specific castable alloys. These are generally non‐ferrous metals such as zinc, aluminum and magnesium.
If a component requires a material that cannot be made by die casting like stainless steel then CNC machining is your single option left. But this procedure creates more material waste.
When both procedures are possible then die casting typically uses standard alloys. These alloys developed for casting are budget friendly. However in special scenarios specialty die‐cast alloys are needed and they are very expensive which can decrease the usual performance edge of die casting.
Die casting gives another benefit for typical materials such as aluminum. Sprue material in die casting is usually recoverable and also can be reprocessed to use again. This helps minimize your net material cost comparatively more than CNC machining that may not retrieve chips to the same extent.
Result: The advantage of low material price of die casting remains valid if you employ common casting metals. If your material & design needs are compatible then picking die casting can cut down on material costs.
Also See: How to Calculate CNC Machining Costs for Your Project
To Sum Up
CNC machining has a greater material cost as compared to die casting because it produces more waste and uses materials less properly. Certain applications demand CNC machining, specially when manufacturing in small batches, working with specialized materials or demanding very strict tolerances.
On the other hand engineers who want to minimize waste and expense usually select die casting where it suits best. By knowing the differences in material costs between these procedures, manufacturers & engineers can pick the best one for their manufacturing and budget requirements.
If you want a dependable partner for CNC machining or die casting then Richconn is the best option. Our team will handle your project in the most economical way. You can contact us at anytime.
Related Questions
In higher volumes (1,000 to more than 5,000 components), die casting is often comparatively less in cost per part which includes material, labor and energy. For specialty materials or short‐run batches (less than 500 components), CNC machining may be a more budget‐friendly pick.
Yes it is possible. Several engineers use a die casting to make the basic shape and then use CNC machining to incorporate accurate features. This hybrid strategy combines speed, accuracy & cost savings.
CNC machining gives very tight tolerances, from ±0.01 mm to ±0.001 mm. Whereas die casting offers loose tolerances, around ±0.1 mm for a 25mm part; furthermore it usually needs extra machining to comply with stringent requirements.
