In its broadest sense, fluid handling refers to managing and manipulating fluids, including transferring, controlling flow, measuring, mixing, and separating them. These systems play a crucial role in various industries, ensuring the efficient movement and control of liquids or gases. Essentially, any industry that uses liquids or gases in its processes relies on efficient fluid handling systems to ensure proper operation, safety, and product quality. These systems often incorporate machined plastic parts to facilitate the precise handling and distribution of fluids in a controlled manner.

Fluid Handling Applications

Because fluid handling is so broad, its systems are used in a large number of industries and applications. Some of the most common include:

  • Power generation and transportation – Cooling systems in power plants and engines necessitate effective fluid handling for heat transfer and lubrication.
  • Chemical and pharmaceutical processing: Fluid handling systems are needed for manufacturing and handling chemicals, drugs, and other sensitive liquids.
  • Food and beverage industry – This industry relies on fluid handling systems for processing, packaging, and dispensing food and beverage products.
  • Water treatment – Fluid handling systems are used extensively by municipalities for delivering clean water and managing wastewater.

While the industries and the fluids being handled are vastly different, many require the same types of plastic machined components, including sprockets, spur gears, flanges, wear strips and shoes, wheels and rollers, valve fittings, seals, impellers and propellers, bearings and bushings, flow meters and sensors, and more. Larger parts, such as those used by municipalities for wastewater, are ideal for machining because, typically, the volumes are lower, and it’s more economical than injection molding or other manufacturing methods.

Common Requirements for Machined Components

Machined plastic parts within fluid handling systems are designed to meet specific requirements such as surface finish, tight tolerances, durability, and compatibility with various fluids. Precise engineering and machining allow for seamless integration within these complex systems, maintaining the integrity and functionality of the system and ensuring smooth operation and optimal performance.

While parts can be fully machined, a common and often preferred method is to start with an injection molded near-net shape, and then add machined features, such as surface finish, tolerances, and threading to meet the component’s specifications.

Partnering with a manufacturer of plastic machined parts that will work with you to understand your needs and specifications is critical. They should have processes in place to ensure repeatability from part to part, as well as quality control testing equipment to ensure specifications are met.

Common requirements include:

  • Surface finish – Surface finish specifications are required for parts that impact sealing, mating, and pressurizing to prevent leakage or contamination. For components requiring fluid flow (impellers, channels), a smooth finish minimizes friction and pressure loss. Seals and gaskets may require a slightly rougher finish, which can improve grip and sealing effectiveness.
  • Dimensional accuracy – Exacting tolerances can be critical for components used in fluid handling systems to ensure proper fit and alignment. Valves, seals, and other critical parts may require tight tolerances to ensure a precise fit and leakproof connections. Other non-critical components may allow looser tolerances.
  • Geometric tolerances – Roundness, concentricity, and other geometric tolerances might be crucial for smooth operation and proper functionality of some components.

Why Use Plastic Components in Fluid Handling Systems

Material choice plays a significant role in ensuring your components work within the system effectively. Plastics are often chosen over metals for these components because of the additional benefits.

  • Corrosion resistance – Certain plastics, like PTFE and PEEK, excel in environments where metals would corrode due to harsh chemicals or moisture. This eliminates the need for expensive coatings and reduces maintenance costs.
  • Lightweight – Plastic components are significantly lighter than their metal counterparts, reducing the weight burden on equipment.
  • Noise reduction – Plastic gears and sprockets operate quieter than metal ones, contributing to a more pleasant working environment and potentially meeting noise regulations in specific industries.
  • Self-lubrication – Some plastics, such as acetal, offer self-lubricating properties, reducing the need for external lubrication and simplifying maintenance. This is an advantage in applications where lubrication might contaminate fluids.
  • Design flexibility – Plastics offer much greater design flexibility than metals due to their machinability and ability to be molded into complex shapes.

Ultimately, choosing between plastic and metal for a particular component depends on carefully evaluating the specific application requirements and weighing the advantages and disadvantages of each material. Consulting with a design engineer and machining expert can ensure you make the optimal choice for your fluid handling system.

Choosing the Right Plastic for Fluid Handling Components

Material choice is critical as it can impact the functionality and longevity of component. Poor material choice could have catastrophic impact within your fluid handling system. Consider all the material’s characteristics to ensure they will meet the requirements of your application. Also, ensure all other materials and hardware are compatible.

  • Chemical compatibility: To prevent degradation or contamination, the material and surface finish must be compatible with the handled fluids.
  • Corrosion resistance: Unlike metals, plastics are often inherently corrosion resistant, making them ideal for harsh chemical environments. However, different plastics have different resistance levels, so selection must be based on the specific environment of the system.
  • Strength and durability – The material should have sufficient strength to withstand operating pressures and mechanical loads, including any impacts or vibrations.
  • Wear resistance – This is especially important in parts with moving contacts or those exposed to particulates in the fluid; the material should resist wear to maintain its dimensions and performance over time.
  • Temperature resistance: Material selection should ensure dimensional stability and functionality at operating temperatures.
  • Thermal expansion – Consideration of the coefficient of thermal expansion is important, as various materials will expand or contract differently under temperature changes, potentially affecting tolerances and fit.
  • Permeability – Materials must be selected to minimize the absorption of fluids, which can lead to swelling, loss of mechanical properties, or contamination of the fluid system.
  • Regulatory and safety compliance – Materials used in systems that are used in food processing, medical, or pharmaceutical applications must meet specific regulatory requirements for safety and compatibility. In environments where fire risk is a concern, the flammability rating of the plastic material is a crucial factor.
  • Costs – The cost of the material can vary widely, impacting the overall cost of the finished part. This must be weighed against other characteristics and requirements of the part.

While machined plastic excels in valves, fittings, and seals, its versatility extends to various other fluid-handling components. Here are some specific parts and materials that may be appropriate.

  • Sprockets and gears in low-to-medium torque applications in pumps, mixers, and conveyor systems – Acetal (polyoxymethylene (POM)), polycarbonate (PC), and nylon (polyamide (PA)) offer good strength, wear resistance, and low noise operation.
  • Wear strips and liners that protect metal components from wear in pumps, valves, and pipelines, especially in abrasive environments – Ultra-high-molecular-weight polyethylene (UHMWPE), Polytetrafluoroethylene (PTFE), and PA provide excellent wear resistance and low friction, reduce maintenance costs, extend component life, and offer good chemical resistance.
  • Impellers and propellers for low-flow pumps, mixing systems, and agitation applications – polypropylene (PP) and PVDF (polyvinylidene fluoride) offer good chemical and corrosion resistance and lightweight properties, making them more energy efficient.
  • Bearings and bushings in low-load rotating components in pumps, valves, and other mechanisms – POM, PTFE, and PA offer low friction, self-lubricating properties, corrosion resistance, and good noise reduction.
  • Flow meters and sensor housings and components – PC and PA offer good transparency and machinability for complex shapes and can be designed for specific flow requirements.

Material selection depends on specific application factors like pressure, temperature, chemical compatibility, and required strength. Each application may have unique requirements, making it essential to evaluate these considerations in the context of the specific fluid handling and control system. Consulting a plastic machining expert is crucial for optimal material and design choices.

Ensinger: The Plastic Experts

Our plastics experts have decades of experience designing and machining parts that meet exact specifications. From material selection to tight-tolerance machining, quality is our top priority. We understand the critical role these components play in your system’s performance. That’s why we leverage our deep knowledge of materials, processes, and quality analysis to deliver parts that function flawlessly.

Cost-effectiveness matters, too. We collaborate closely with you to understand your specific needs and application. This allows us to optimize designs, focusing high precision on critical areas while ensuring non-functional elements meet requirements. This results in parts that are both high-quality and budget conscious.

Let us help you achieve optimal performance and cost-efficiency in your fluid handling system. Contact us to get started.