This article will give a detailed discussion on metal shims.
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Shim Definition: A shim is a material used to fill gaps or spaces, often in construction and mechanical applications. Commonly used in window and door jamb construction, shims can be crafted from readily available materials for tasks like leveling a table, or from metal for larger machinery. They are essential for a wide range of purposes, ensuring proper alignment and functionality in assemblies, especially in mechanical devices where precision is crucial.
Shims are often used as compensators to fill small gaps between components within a device. Typically made of metal, these small, delicate objects prevent internal parts from colliding due to loose fittings, which could otherwise cause significant damage. Since these parts are often critical to a machine's operation, any damage could easily compromise its functionality. By fitting into these gaps, shims not only help save on manufacturing time and costs but also enhance the equipment's longevity.
Shims are produced using various methods. Below, we explore some of the most common techniques.
The initial step in shim manufacturing involves creating tools according to the specific shim specifications. Die-cast steel rules, which function similarly to cookie cutters, are commonly used. A sharp, pre-shaped steel rule die is applied to the shim material to cut the desired pieces.
For each new order of shims, steel rule dies are custom-made. To minimize the one-time tooling cost, economically sound materials are used for tooling, allowing repeat customers to reorder the same shims without incurring additional fees. After the die is made, the material is selected and cut on a stamp press machine. Cutting shims on the stamp press requires precision to minimize material waste. Once cut, the shims undergo deburring to ensure smooth edges. Finally, the shims are inspected for edge quality and accuracy before being packed for shipment.
The manufacturing process for stamp press shims involves four main steps:
Metal shims are generally not cut using a stamping press, as this method can quickly degrade the die.
The CNC laser cutter follows a process similar to that of a stamp press, but with key differences. Instead of requiring a custom steel rule die, the laser cutting machine is programmed to use its laser to cut the shims precisely. This method is commonly used to cut metals and other shim materials. While the shim production process still involves four steps, the key distinction is that the operator programs the machine to the desired specifications, eliminating the need to manually select material and tooling.
An abrasive separation technique for shaping metal shims is water jet cutting. An abrasive (grinding powder) is introduced to the water jet during metal cutting. When under high pressure, the water jet precisely slices the workpiece without emitting heat or causing light to reflect, as is the case with laser cutting. This procedure is thus appropriate for materials that are sensitive to temperature.
Wire-cut EDM is an exceptionally precise electrothermic separation method used for cutting conductive materials, particularly metals. Unlike traditional cutting techniques like drilling, milling, or turning, this process generates an electrical charge between the cutting wire and the workpiece, which in this case is the metal shim, to separate material instead of mechanically removing it.
Turning, like milling and drilling, is a machining method that falls under the category of cutting techniques. In this process, the shim is secured into the turning machine, which rotates around its axis while material is removed until the desired shape is achieved. Turning is primarily used to create round pieces and is often the initial step in a process chain, as it forms the general shape of the part.
Punching is a manufacturing process that utilizes a punch press to create specific shapes in a workpiece. The process requires a tool consisting of two parts: a punch, which is internally shaped, and a die, through which the punch fits perfectly. The concept is similar to how a hole punch operates. An alternative to traditional punching is punch nibbling or nibbling, a method where multiple punches are used incrementally to produce complex geometries or larger holes.
In the United States and Canada, various machines are available for producing metal shims. These machines are crucial for the precise and efficient manufacturing of metal shims, which are widely used to fill gaps, align machinery, and ensure accurate fitment of parts, contributing to the smooth functioning of equipment and structures. Below, we examine several leading machines and their unique features.
The Trumpf TruLaser series of laser cutting machines are well-known for their high precision, speed, and versatility. They utilize fiber laser technology, which offers excellent cutting capabilities for various metal thicknesses and types. These machines can handle complex shapes and provide clean, smooth edges. The TruLaser series also includes automation features like automatic sheet loading and unloading, enabling efficient production.
The Omax 80X series of waterjet cutting machines are preferred for their ability to cut metal shims and other materials without heat generation, which minimizes thermal distortion. Utilizing an abrasive waterjet stream, these machines achieve intricate designs and high accuracy. They often come with advanced software for precise programming and efficient material use, making them a popular choice across various industries.
The Amada AE series turret punch presses are renowned for their high-speed punching and forming capabilities, providing consistent accuracy in metal shim production. Designed to handle various materials and thicknesses, these machines are versatile for different applications. The AE series also features user-friendly CNC controls for straightforward programming and setup.
The Haas VF series of CNC machining centers are well-regarded for their robust construction and reliability. These machines can perform precision machining on metal shims, creating complex shapes and features with high accuracy. Haas VF series machines are equipped with advanced control systems and tooling options, making them versatile for different production needs and batch sizes.
The Komatsu H1F series stamping presses are ideal for high-volume metal shim production, featuring advanced die and punch technology for precise cuts. Known for their fast cycle times, durability, and efficiency, these presses are favored in the metalworking industry for large-scale operations.
Keep in mind that technology and market trends evolve quickly. For the latest and most accurate information on leading metal shim production machines in the United States and Canada, it's important to conduct thorough research and consult with industry experts.
Metal shims are categorized based on their material composition. The most commonly used metals include stainless steel, aluminum, brass, copper, and carbon steel.
Stainless steel shims offer precise thickness and exceptionally smooth surfaces, making them ideal for axially spacing objects along a shaft. They are commonly used to create the necessary gap between a bearing and a rotating component. Stainless steel shims are particularly suitable for environments prone to corrosion.
A steel alloy with a minimum bulk content of 10.5% or 11% chromium is known as stainless steel. Industrial shims and washers are frequently made of stainless steel because they do not rust, corrode, or discolor as easily as regular steel. When the alloy type and grade are not specified, it is sometimes known as corrosion-resistant steel, or CRES. The level of chromium in stainless steel sets it apart from carbon steel. A passive layer of chromium oxide occurs on the surface of stainless steel when there is enough chromium present to prevent additional surface corrosion and the spread of corrosion into the metal's internal structure. The number of stainless steel grades exceeds 150.
Austenitic stainless steels are renowned for their superior resistance to staining and atmospheric corrosion in both oxygenating and non-oxygenating environments. Although austenitic stainless steel can become magnetic during cold forming, it is non-magnetic when annealed. Among the various 300 series stainless steel grades, alloying elements influence factors such as corrosion resistance, operating temperature range, magnetism, formability, and welding characteristics. Grade 316 stainless steel is particularly suitable for applications involving chemicals, petrochemicals, food, and marine environments due to its exceptional strength, ductility, toughness, and corrosion resistance. The addition of molybdenum further enhances its corrosion resistance. Grade 316 is highly effective for making metal shims, metal packers, and certain spring applications.
Aluminum shims are small, horseshoe-shaped plates used to level uneven surfaces. Aluminum stands out for its corrosion resistance due to its passivation process and low density. While it generally resists corrosion well, different aluminum alloys offer varying levels of corrosion resistance and strength.
Aluminum shim stock has a variety of applications, including but not limited to the following:
Aluminum shims are lightweight and commonly used in structural components across various industries, including aerospace, construction, and transportation. For quick turnaround of shims, spacers, and washers, standard thicknesses range from 0.05mm to 3mm (0.002" to 0.125").
Aluminum shims are designed with ridges to prevent separation when stacked, allowing them to support heavier weights compared to plastic tapered shims. They are ideal for aligning shafts and axles. For added stability, screws can be used through the center mounting hole. Commonly known as pinion shims, wedge shims, and tapered wedge shims, these are easy to use for leveling and aligning dead loads.
Using laminated shims provides benefits such as cost savings through faster attainment of close tolerances and reduced assembly time. The choice of laminate material should match the application requirements; for example, aluminum is suitable for applications with temperatures below 300°F and no pressure.
Aluminum is often chosen for applications where weight is a critical factor due to its extremely low density. Its low reactivity makes it highly desirable in industries like food and beverage, and it also offers exceptional corrosion resistance.
Aluminum is favored for its widespread availability, relatively low production costs, and excellent recyclability. It can be fully recycled while retaining its original properties. In Europe, for instance, 42% of cans and 95% of aluminum used in vehicles are recycled.
As mentioned earlier, aluminum is abundant, but this is not the main reason for recycling. The primary motivation is that recycling scrap aluminum requires less than 5% of the energy needed to produce aluminum from ore. This makes reusing discarded material more cost-effective and environmentally friendly.
Aluminum is often alloyed with elements like copper, zinc, magnesium, manganese, and silicon to improve its mechanical properties. These alloys are used in various applications similar to those of household foil and beverage cans. For instance, aluminum foil is commonly made from an iron and silicon alloy to enhance its characteristics.
Aluminum is an ideal material for shims and foil when weight and cost are significant factors. Its lightweight and malleable properties make it essential for precision applications in various industries, offering both affordability and functionality.
Brass shims are highly versatile, offering a balance of stiffness and corrosion resistance. They are ideal for applications requiring durability and can be easily stamped, bored, cut, machined, sheared, and drilled. Brass shims typically undergo cold rolling to achieve a half-hard temper.
Brass shims are versatile and widely used across various industries, including plumbing, automotive, heavy industrial, and construction. They also find applications in model trains and airplanes. Key uses include:
Brass, an alloy of copper with distinctive properties, is well-suited for shims due to its specific characteristics. Here are some key properties of brass:
Shims are commonly used across various industries, particularly those involving machinery. They are essential for closing gaps, leveling surfaces, achieving precise alignment, and compensating for wear, which helps reduce the need for frequent replacement of more expensive components.
Typically, shims must be manufactured to specific sizes and thicknesses to serve as space fillers or enhance alignment. Brass is well-suited for this application due to its softness, lower melting point, and higher malleability compared to bronze and zinc. It is also easier to cast, making it an ideal choice for shim production.
Brass has a low coefficient of friction, making it an ideal choice for applications where sparking must be avoided, such as around explosive gases. It is also an excellent conductor of heat and electricity. Despite its softness, brass is more durable and robust than copper. The strength of brass depends on the proportions of copper and zinc used in its alloy.
Brass is commonly used for pipes and tubing in aquatic conditions due to its excellent corrosion resistance. It also resists corrosion in environments with alcohol, fuel, oil, kerosene, or gasoline, and has a high resistance to tarnishing.
Approximately 90% of brass is recycled. Its high recyclability is partly due to its lack of ferromagnetism, which allows it to be easily separated from other metals using magnets to remove magnetic materials.
Brass possesses antibacterial qualities, just like many copper alloys. Brass helps eliminate some bacteria and diseases because of the copper it contains. This quality makes brass a viable option for shims utilized in situations like the food industry or hospitals where sanitation may be particularly crucial. The kind of bacteria present and the media they are in will also determine how rapidly they are eliminated.
Carbon steel shims are galvanized to prevent rust and corrosion over time. Featuring a horseshoe design, they can be used to level and pack structures that are already secured to a surface.
Examples of applications include:
Shims play a crucial role in industrial operations and come in various types depending on the metal used, their intended use, and their design. The term "shim" is a broad category encompassing a wide range of specialized shims for different purposes. It is incorrect to assume that all shims are identical or serve the same function; like other industrial tools, shims are designed to meet specific needs and applications.
Edge bond shims are utilized for precise adjustments between parts and assemblies. They consist of 20 to 80 layers of foil that can be peeled off incrementally for fine-tuning. These shims are specifically designed to fit into gaps within equipment and integrate seamlessly into the assembly.
Tapered shims are employed on tapered surfaces to tighten assemblies by separating components. They are often inserted into an assembly and may remain integrated within the assembly to maintain proper alignment.
Peelable shims, like edge bond adjustable shims, are constructed in layers that can be peeled away to achieve the desired thickness. Typically available in thicknesses of 0.002 to 0.003 inches (0.058 to 0.0762 mm), they allow for precise, incremental adjustments.
Arbor shims, also known as slitter shims, are thin, washer-like discs designed to prevent axial movement. Made from high-tolerance materials for a precise fit, they are used on milling cutters, saws, and grinding tools to reduce wear by separating contacting surfaces.
Variable shims, also known as lengthening or shortening shims, are used to adjust the length of stripper bolts in punch and die assemblies. They help increase or decrease shaft or bolt lengths, offering a cost-effective solution for precise adjustments. Variable shims are measured by their thickness, inner diameter (ID), and outer diameter (OD), similar to arbor shims.
Shim rings, also known as tolerance rings, are employed to ensure a tight fit for bearings in stamped, molded, or worn housings. They function similarly to arbor shims by preventing axial movement and absorbing play between components. Shim rings act as a buffer to protect connected parts from damage and are commonly used in gearboxes and gear systems.
Slotted shims, also known as slotted motor shims, have a horseshoe-like shape with a thin rectangular form and a slot cut into one side. This design facilitates easy alignment and adjustment. They are used to balance and precisely align machine components, ensuring repeatable accuracy and preventing equipment damage. Slotted shims offer a cost-effective, efficient method for achieving precise alignments.
Shim stock is a versatile material used to create custom shims. It can be cut to various dimensions and sizes with metal shears, making it ideal for leveling, adjusting, and fitting purposes. Shim stock is measured by its thickness, length, and width, which are used to order the material.
Precision metal shims are used in various oil and gas industry applications. Metal shims are frequently utilized in various parts, including pumps, compressors, turbines, motors, gearboxes, and torque converters. Throughout the entirety of the equipment's life cycle, from assembly to installation to refurbishment and retrofitting, they can result in cost and labor savings. Below are some of the uses of metal shims in the oil industry:
Even with precise measurements, achieving a perfectly square door or window during installation often requires adjustments. Instead of cutting a new frame or making extremely precise adjustments, shims are used to fill gaps between the window or door casing and the framed opening.
To level and plumb the element, begin by wedging a shim between the frame and the adjacent stud, using a level to ensure the door or window moves toward the desired position. Gently tap the shim into place with a hammer or mallet. If the first shim doesn't provide the necessary adjustment, place a second shim next to it, oriented in the opposite direction. Avoid driving the shims in too deeply, as they are difficult to remove once in place. Once the door or window is level and plumb, secure it by driving a nail or screw through the casing, shims, and framing. Finally, use a utility knife to score and break off any excess shim length once the window or door is firmly in place and fastened.
Metal shims are versatile tools not limited to just windows and doors. They can also be used to level a wobbly toilet, square up cabinets, adjust subflooring and floorboards, and prevent outdoor decking from creaking. Additionally, metal shims serve the following domestic purposes:
Copper shims help reduce maintenance costs by offering a more affordable alternative to repairing or replacing entire machines when they become damaged. They eliminate the need for additional labor associated with machine repairs, resulting in overall savings for a business's budget.
Additionally, copper shims are highly valued for their compatibility with heated and electrical applications. Copper's ability to withstand high thermal and electrical voltages makes it ideal for cabling and other similar uses. Its softness and malleability also make it an excellent choice for leveling, spacing, and sealing applications, allowing for easy customization.
Finally, copper shims are highly sought after for their exceptional corrosion resistance. They are especially valuable in industries involving water transfer and piping applications, as copper is non-reactive to water. This material remains robust and visually appealing in most conditions, with minimal corrosion.
While brass shims offer advantages similar to those of copper shims, they differ in several key ways:
Brass, being a softer metal, has a lower friction rate compared to other materials. This characteristic makes brass shims suitable for environments where sparking must be minimized, such as applications involving explosive gases. Additionally, brass excels as a conductor of heat and electricity and, despite its softness, is stronger than copper.
Stainless steels, in contrast, are among the strongest materials for shims, offering exceptional durability, corrosion resistance, and strength. High-quality stainless steel resists corrosion from acids and alkanes, making it ideal for use in the pharmaceutical and petrochemical industries, as well as in applications that demand high temperature tolerance and durability.
Aluminum may be the best shim material when seeking something lightweight. Shims made of aluminum can also endure high temperatures. The fact that these shims are comparatively non-oxidizing is another desirable quality. Because of this, the shelf life of an aluminum shim is quite extensive.
Certain applications require heavy-duty shims that can withstand harsh conditions. Large industrial machinery exposed to corrosives, biological agents, and volatile compounds is prone to degradation. Brass shims are often used in these scenarios, particularly in saline environments, due to their durability and resistance.
Each shim material possesses distinct strengths and weaknesses, making it essential to consider the material's properties when selecting the appropriate shim. This ensures that the shim is well-suited for the specific application. For example, plastic shims are unsuitable for high-temperature applications, while stainless steel shims are ideal. Additionally, some materials are better suited for marine conditions due to their resistance to saltwater corrosion.
When selecting the right shim, it's important to consider the material’s composition as well as its mechanical and physical properties. Shims come in various materials and thicknesses, including plastic, aluminum, brass, stainless steel, and cold-rolled low-carbon steel. These materials are commonly used and generally meet the design requirements for most applications. However, specialty applications may require additional materials tailored to specific needs.
Choosing the right shim material is crucial for effective design. For high-temperature engine applications, plastic shims are generally unsuitable; instead, stainless steel or cold-rolled materials are preferred. Similarly, ferrous metals like cold-rolled or stainless steel are not ideal for marine environments due to their susceptibility to corrosion. In such cases, brass shims are a better choice as they resist saltwater deterioration effectively.
Another important consideration when choosing a shim is its intended usage. For instance, shims used in settings with static loads must be able to effectively occupy mechanical space or gaps. Some metals are better at preventing static load and static discharge than others. Additionally, factors like friction and drag wear need to be taken into account, as they often serve as primary selection criteria in many applications.
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