A Complete Guide to Shim Stock
⏱️ Estimated reading time: 6–8 minutes
Shim Stock Materials Explained
Shim stock is available in a variety of metal types, each selected for its specific characteristics—such as corrosion resistance, strength, or conductivity. Below is an overview of the core materials used in shim manufacturing:
304 Stainless Steel
304 stainless steel is one of the most commonly used materials for shim stock due to its excellent balance of strength, corrosion resistance, and workability. As an austenitic stainless alloy containing around 18% chromium and 8–10% nickel, 304 resists oxidation and chemical exposure better than standard carbon steels. It is non-magnetic in its annealed state and maintains strength even at cryogenic temperatures, making it suitable for both industrial and marine environments.
In shim applications, 304 is typically supplied in full-hard condition to maintain rigidity at thin gauges. Full-hard 304 stainless has a tensile strength of up to 1,275 MPa (185 ksi) and can be manufactured in thicknesses as thin as 0.05 mm. This makes it an ideal choice when a durable, corrosion-resistant spacer or alignment solution is required. It is commonly used in food production equipment, structural assemblies, machinery frames, and general-purpose alignment tasks where long-term corrosion resistance is critical.
304 vs 316 stainless steel grades316 Stainless Steel
While 304 offers excellent general-purpose performance, 316 stainless steel is chosen for applications requiring superior corrosion resistance—particularly in environments with chlorides, such as coastal, chemical processing, or medical settings. The primary difference is the addition of molybdenum in 316, which improves its resistance to pitting and crevice corrosion from saltwater or aggressive industrial chemicals.
Mechanically, 316 is similar to 304 in terms of tensile strength and formability, but with a slightly softer edge in full-hard condition. It is often used in marine fasteners, offshore equipment, pharmaceutical tools, and surgical components—areas where hygiene, corrosion resistance, and strength are all important. Shim stock in 316 is commonly available in thin gauges, such as 0.05 mm to 1.0 mm, and up to 6.0 mm for more robust industrial spacing applications.
Brass Shim Stock
Brass is a copper-zinc alloy that is valued for its ductility, formability, and resistance to corrosion—particularly in water, fuel, and mildly acidic environments. It is a non-magnetic metal that combines aesthetic appeal with excellent mechanical properties, making it popular in both decorative and functional roles.
Brass shim stock is easy to cut, punch, or laser-process, which makes it suitable for on-site modifications or rapid prototyping. It also offers moderate electrical conductivity, making it useful in electrical terminals, low-voltage contact surfaces, and EMI shielding. In mechanical assemblies, brass is often used to create low-friction surfaces, bearing spacers, or vibration dampeners. Typical thicknesses range from 0.05 mm to 1.0 mm, and it is especially favoured in applications that require precise yet soft fitting shims.
Copper Shim Stock
Copper offers the highest electrical and thermal conductivity of all commercially available metals, which makes it a top choice in electrical, electronic, and heat-transfer applications. Shim stock made from copper is typically manufactured from C110 alloy (99.9% pure), which is soft, highly ductile, and easy to form or cut.
In technical applications, copper shims are used for grounding, shielding, and thermal interface layers. They’re also found in transformer assemblies, EV battery housings, and custom power distribution components. Copper also provides good resistance to atmospheric corrosion and is suitable for use in mildly aggressive environments, especially where long-term conductivity and flexibility are essential. Commonly supplied in thicknesses from 0.125 mm to 0.5 mm, copper shim stock can be layered, stamped, or laser-cut depending on project needs.
Thickness & Tolerances in Shim Stock
Shim stock is available in an exceptionally wide range of thicknesses, allowing for precise spacing, leveling, and alignment in mechanical assemblies. Whether adjusting clearance between components or fine-tuning the position of a tool or die set, having access to tightly controlled thicknesses is essential.
At Shim Stock Metals UK, we supply materials ranging from as thin as 0.05 mm up to 6.00 mm, depending on the metal type. Thin gauges such as 0.05 mm, 0.10 mm, and 0.20 mm are commonly used for precision applications, including bearing shims, gap adjustments, and custom laser-cut spacers. Thicker materials (up to 6 mm in stainless steel) are ideal for heavy-duty alignment, mounting, and fabrication tasks where compressive load or structural integrity is a factor.
Tolerances vary depending on the base material, temper, and method of manufacture. For example, full-hard 304 stainless steel shim stock typically adheres to a tolerance of ±0.0127 mm (±0.0005 in) at 0.127 mm (0.005 in) thickness. Thinner gauges often have tighter tolerances, while thicker stock may allow for slightly wider ranges. Precision-rolled coils and sheets can meet more exacting standards, especially when used for CNC laser cutting or die stamping.
When working with shim stock, it’s important to consider stacking limits. While multiple layers can be used to build up a required thickness, excessive stacking (more than four shims) may reduce stability or introduce unintended flex or vibration. For this reason, many engineers prefer to use custom-cut shims in the exact thickness required.
To assist with measurement conversions, Shim Stock Metals UK also provides a Thou to mm chart, which is especially useful for engineers and technicians working across metric and imperial systems.
Need to estimate weight before placing an order? Try our Metal Weight Calculator to calculate the mass of your shim material in grams, kilograms, or pounds.
Applications and Industries
Shim stock plays a critical role across a wide range of industries by helping to control tolerances, level surfaces, align components, and eliminate mechanical play. Whether in heavy industrial environments or delicate electronics assemblies, shims are essential for ensuring performance, safety, and longevity.
In the aerospace industry, shims are used to adjust the alignment of structural components, compensate for accumulated manufacturing tolerances, and ensure tight control over aerodynamic surfaces. Both stainless steel and copper alloys are used, with laser-cut or stamped profiles tailored to each aircraft platform.
The automotive sector relies heavily on shim stock during both assembly and maintenance. Shims can be used to adjust valve clearances, reduce vibrations in brake systems, or act as wear plates between dynamic components. With the growing focus on electric vehicles (EVs), conductive copper and brass shims are also being deployed in battery assemblies, grounding systems, and EMI shielding layers.
In industrial maintenance and repair operations (MRO), shim stock is an everyday essential. Technicians use slotted shims to align machinery bases, mount motors, or level jigs and fixtures. Pre-cut and laser-shaped shims dramatically reduce downtime and improve setup repeatability in CNC and fabrication environments.
The marine sector often requires corrosion-resistant materials, making 316 stainless steel an ideal choice. Shims are used to align prop shafts, stabilize deck fittings, or reduce vibration in engine installations. Given the harsh exposure to salt and moisture, dimensional stability and material purity are crucial.
In electronics and electrical systems, shim stock made of copper is prized for its high conductivity. Applications include grounding layers, thermal interfaces for heat sinks, EMI shielding gaskets, and battery contacts. The thin profile of shim stock enables it to fit into compact assemblies without adding bulk or weight.
Even medical and precision tooling industries benefit from shim stock. In surgical robots, imaging devices, and other diagnostic systems, 316 stainless steel is often used to finely adjust calibration settings or stabilize parts within extremely tight tolerances. The biocompatibility and corrosion resistance of 316 make it especially suitable for cleanroom and sterile applications.
Across all these industries, custom cutting techniques such as laser cutting, stamping, and waterjet enable shims to be fabricated in virtually any shape. These methods ensure burr-free edges and consistent profiles, enhancing the performance and longevity of shim-based adjustments.
How to Use Shim Stock
Whether you're working with loose sheets, rolled coil, or precision laser-cut profiles, using shim stock correctly ensures optimal fit and function. The process is generally straightforward, but accuracy in measurement and material handling is key.
The first step is to determine the required shim thickness. This is typically done using feeler gauges, stackable shims, or by carefully measuring the clearance between components with a micrometer. It's essential to choose a thickness that provides the right balance between alignment and mechanical stability.
Next, select the appropriate material based on the operating environment. For general indoor use, 304 stainless steel or brass may suffice. In harsher settings, such as marine or chemical processing environments, 316 stainless steel may be more suitable. Copper may be selected for electrical or thermal purposes where conductivity is required.
If you're not using precut slotted shims , the next step is to cut the stock to the required shape. Simple shapes can be sheared with tin snips or punched with hand tools, while more complex geometries benefit from laser cutting, waterjet machining, or CNC punching. For frequent jobs, investing in a custom die or punch set can reduce waste and speed up production.
Finally, install the shim or shim set in place, ensuring there is no binding, warping, or slippage. In dynamic assemblies, such as rotating shafts or thermal expansion zones, it's especially important to verify that the shim remains seated and aligned over time. Some setups may require adhesive-backed shims, while others may benefit from pre-slotted designs for easy removal and adjustment.
Correct usage of shim stock not only improves equipment performance but also extends the lifespan of mating components by reducing wear, misalignment, and vibration.
Frequently Asked Questions
Shim stock is used to adjust spacing, alignment, and tolerances in mechanical assemblies. It's widely applied across industries like aerospace, automotive, electronics, and industrial maintenance to ensure precision and stability between components.
Common shim stock materials include stainless steel (304 and 316), brass, and copper. Material choice depends on factors like corrosion resistance, conductivity, and the specific mechanical or electrical environment.
Shim stock is available in thicknesses ranging from 0.05 mm to 6.00 mm, depending on the material. Thin gauges are ideal for precision work, while thicker shims support heavy-duty alignment and load-bearing applications.
Shim stock can be cut using tin snips, punches, or for more intricate shapes, with laser cutting, waterjet, or CNC machines. Choosing the right method depends on material thickness and project complexity.
Yes, shims can be stacked to achieve a specific thickness. However, it's best to limit stacking to four layers to maintain stability and avoid flex or vibration. For better performance, custom-cut shims to the exact thickness are recommended.
Conclusion
Shim stock is an indispensable tool for engineers, technicians, and fabricators working across industries that demand precision and adaptability. Whether you're aligning aerospace components, adjusting automotive parts, or building high-performance electrical systems, the right shim stock helps deliver optimal results.
At Shim Stock Metals UK, we focus on supplying high-quality shim stock in stainless steel, brass, and copper, with a full range of thicknesses and the option for custom laser cutting. Backed by years of experience and technical expertise, we are committed to helping customers find reliable solutions for even the most demanding applications. You can find more technical guides and resources in our Knowledge Hub.
Explore our full product range, browse our Thou to mm chart, or contact us directly to discuss your shim requirements. We're here to support your precision engineering needs—no matter the scale or complexity.
