High-precision manufacturing is crucial in certain industries, particularly aerospace and medical. Therefore, the best ways to create such parts are always needed. While there are many high-precision manufacturing technologies, manufacturers still need to follow some guiding principles to ensure fabrications stay consistent with the set precision and tolerance specifications. Here’s where this article proves important.
We discussed tips on obtaining high-precision metal and plastic parts, including the go-to manufacturing techniques for fabricating them. Read ahead!
Tips on How to Get High-Precision Metal and Plastic Parts
Manufacturing industries like aerospace, automotive, and medical prioritize getting high-precision parts because deviation from set standards may be detrimental. Below are tips for manufacturing the best high-precision metal parts and components.
- Material Selection
The choice of metal you use can significantly impact the precision of the final product. In manufacturing metal parts, manufacturers like to use aluminum and steel because of their stability and easy machinability, among other features. Likewise, when dealing in plastic parts, machinists ensure that they select engineering-grade plastics like PEEK, ABS, and polycarbonate.
Therefore, select the best material grade that suits your intended fabrication. You do not want to push a material beyond its capabilities. Another aspect to consider in material selection is your supplier. Ensure you partner with a reputable supplier to help avoid contaminated alloys or impurities that may alter your part’s precision.
- Design Optimization
Optimizing the design is another important criterion to consider. It is relatively easier to create designs on your computer, but be sure to consider its manufacturability and ease of creating such structures. Part manufacturers should ensure that they simplify or avoid overly complex features that are difficult to machine, as these details may alter the intended precision standards.
In addition, use design software that allows for precise measurements and adjustments. Another design criterion is tolerance specifications. Parts manufacturers must properly specify tight tolerances and permissible deviations in dimension to ensure all fabricated parts adhere to industry standards.
- Routine Maintenance
Ensure regular maintenance of your machinery and equipment. Operators and technicians should ensure routine oiling of the manufacturing device’s moving parts and troubleshoot the device when necessary. These practices help prevent wear and tear on the machine, optimizing its functionalities for high-precision manufacturing. Routine calibration of the device’s measuring parts is also important to avoid potential deviations that may be detrimental to the parts fabrication process.
- Choice of Manufacturing Methods
The choice of manufacturing method also plays a crucial role in achieving high precision. Ensure that whatever method you select for your parts fabrication suits the intended design, including its tight tolerance specifications, among other important design details.
Fabrication shops and facilities should not hesitate to invest in high-quality machines and tools to ensure consistent results and build customer trust and reputation. When manufacturing parts using processes like injection molding and die casting, create the mold using the right material and manufacturing processes. Molds should be designed to accommodate shrinkage and other material-specific behaviors.
- Skilled Operators and Technicians
Employ skilled operators, machinists, and technicians to ensure your parts and components attain all the intended standards. Having experienced staff will prove effective in delivering quality fabrications that adhere to all intended standards and quality. These operators should be able to make necessary adjustments in the device if there’s a deviation and troubleshoot issues that may arise during the manufacturing process. You may also need to sponsor training and workshops to help improve their skills.
- Controlled Environment
Maintain a controlled environment in your manufacturing facility. Temperature and humidity fluctuations may affect material expansion and contraction during processes like injection molding and die casting. Processes like CNC machining also need process control, such as using appropriate cutting fluids to prevent potential overheating or burning, which may alter precision. Maintain consistent processing conditions such as temperature, pressure, and cooling rates. Variations can lead to warping, shrinkage, and other defects that affect precision.
Manufacturing Methods for Fabricating Metal Parts
The choice of manufacturing methods also plays important role in creating high-precision parts. Below are the go-to methods for creating metal parts.
CNC Machining
CNC machining is a precise manufacturing process that uses computer-controlled machines to remove pieces from a solid block (workpiece) to create the desired part. This technique is particularly designed for fabricating components and parts with tight tolerance and high-precision specifications.
The operation limits the need for human interference, as machinists utilize computer-aided design (CAD) files in combo with computer-aided manufacturing (CAM) techniques to ensure the parts creation. CNC machining includes operations like CNC milling, CNC turning, and CNC drilling, among others.
- CNC Milling: This operation uses computer-controlled rotary cutters to remove material and is suitable for creating complex shapes and structures.
- CNC Turning: Rotates the workpiece against a stationary cutting tool. Often used to create cylindrical and conical parts.
- CNC Drilling: As the name indicates, it creates precise holes in parts using a rotating drill bit.
Because of its versatility and suitability for high-precision parts, the technique is used in industries like aerospace, automotive, medical, etc., where precision standards are a priority.
Pros of CNC Machining
- High precision and dimensional accuracy.
- Suitable for complex and intricate designs without compromising precision and tolerance standards.
- Versatile for a wide range of materials, including metals and plastics.
- Excellent repeatability for mass production.
Cons
- High initial setup and equipment costs.
- Requires skilled operators and programmers.
- Material wastage can be high compared to additive manufacturing.
Metal Casting
As the name suggests, metal casting refers to a series of processes that involve casting metal parts. The manufacturing method involves heating metal into the molten state before pouring this liquefied metal into a pre-made mold cavity, where it cools and solidifies into the desired shape and structure.
While the process is not as precise as CNC machining, it suits fabricating tight-tolerance parts. Metal casting suits the fabrication of complex and large parts without compromising the mechanical properties of the metal alloy used. However, you may need to subject the casted part to appropriate surface and post-processing finishes to enhance its appearance and overall features.
Metal casting includes techniques like die casting, sand casting, and investment casting.
- Die Casting: This is the most used metal casing process for various industrial applications. It involves injecting the molten metal into the pre-made mold under high pressure, making it suitable for high-volume parts production.
- Sand Casting: This metal casting process uses sand molds to create its metallic structures. It is the most common and ideal for large parts and low-volume production.
- Investment Casting: It is used to create detailed parts by coating a wax model with ceramic material, then melting the wax away and pouring molten metal into the cavity, where it cools and solidifies.
- Vacuum Casting: Here, the metal casting process occurs in a vacuum, devoid of air, ensuring the casted part is devoid of gas porosity and other similar defects.
Pros of Metal Casting
- Capable of producing complex shapes with intricate details.
- Suitable for both small and large parts
- Versatile for various metals and alloys.
Cons
- High initial tooling and mold costs.
- Potential for defects such as porosity and shrinkage.
- It requires post-processing to achieve the desired surface finish and tolerances.
Sheet Metal Fabrication
Sheet metal fabrication involves manufacturing parts using thin metal sheets. The process encompasses a series of metal fabrication processes, including cutting, bending, forming, and assembling. In sheet metal fabrication, manufacturers may utilize specific cutting techniques like laser cutting and stamping to shape the metal sheets.
Laser cutting involves using high-powered laser beams to cut precise shapes from metal sheets, while stamping uses a stamping press to cut thin metal sheets using a die. After cutting, the manufacturer bends and reshapes the metal sheets before employing other techniques like forming to create the intended shape, structure, and parts to be fabricated. Sheet metal fabrication may utilize CNC machining capabilities to enhance its precision and dimensional accuracy.
Pros of Sheet Metal Fabrication
- High manufacturing efficiency and speed
- Excellent for large production runs.
- Suitable for creating high-precision parts
- Ideal for creating lightweight parts without compromising strength.
- Cost-effective for high-volume production.
Cons
- Limited to parts that can be made from flat sheets.
- Material properties may change due to bending and forming.
Manufacturing Methods for Fabricating Plastic Parts
Below are manufacturing methods for fabricating plastic components
Injection Molding
Injection molding is one of the most common methods for creating plastic parts. The manufacturing process is comparable to metal casting, as it involves heating the material, in this case, plastic and polymers, into molten form. The liquefied plastic material is then injected into a pre-designed mold, often made of aluminum. The mold is usually designed to fit the shape, dimension, and intended structure of the parts. Therefore, as the plastic cools and solidifies in the mold, it takes shape.
Manufacturers often utilize engineering-grade plastics to ensure they are strong enough to withstand the stress of this process and maintain considerable strength and mechanical properties for the parts’ application. Both thermoplastic and thermosets are suitable for injection molding, though most manufacturers prefer thermoplastics, as they allow remelting and re-molding, even after multiple times injection molding. Common plastics for injection molding include ABS, polycarbonate, nylon, PEEK, polyethylene, etc.
Pros of Injection Molding
- High manufacturing efficiency and speed
- Suitable for large-scale production.
- Capable of producing complex shapes with high precision and repeatability.
- Low per-unit cost for high-volume production runs.
- Excellent surface finish and detail replication.
Cons
- Limited flexibility for design changes once the mold is made.
- It is not cost-effective for low-volume production due to high setup costs.
3D Printing
3D printing is an additive manufacturing process. Unlike other methods with their peculiarities, this manufacturing technique involves building parts in layers from scratch using digital models. The process uses plastic powders and filaments to create the intended parts, offering unparalleled design flexibility and manufacturing capabilities.
This manufacturing technique is soon becoming the go-to process for rapid prototyping. It allows manufacturers to create prototypes that can be used to monitor and confirm if the design will suit the intended application and tolerance specifications.
Below are some of the common forms of 3D printing
- Fused Deposition Modeling (FDM): This form of 3D printing involves using a continuous filament of thermoplastic material, melted and extruded to form layers, creating the intended parts.
- Stereolithography (SLA): In SLA, a UV laser is used to cure photopolymer resin layer by layer, as it prints the plastic structure.
- Selective Laser Sintering (SLS): This type of 3D printing uses a laser to sinter powdered material, bonding it together to create a solid structure.
Pros of 3D Printing
- Ideal for creating complex geometries and intricate designs that are difficult with traditional methods.
- Rapid prototyping capabilities with quick turnaround times.
- Since it is an additive process, it generates minimal material waste.
- Suitable for low-volume production and custom parts.
Cons
- More expensive per part compared to injection molding for high-volume production.
- Surface finish and mechanical properties may vary depending on the technology and materials used.
- Limited material choices compared to traditional manufacturing processes.
Conclusion
Ensuring high-precision parts goes beyond selecting the right manufacturing technology. It encompasses careful attention to material selection, design optimization, skilled operators, and the right manufacturing methods. We have already provided you with these guidelines to ensure the plastic or metal fabrication of high-quality and precision metal and plastic components. When in doubt, do not hesitate to go over this article.
