Wood or Metal Shims: Comparing Based on Applications and Properties


Comparing Wood and Metal Shims


Wood Shims

While it is common knowledge in the manufacturing industry that shims can be as valuable as they are practical, some people may not be aware of the fact that shims come in more than just metal varieties. In fact, wood shims have become just as popular, because they deliver benefits to projects that may not otherwise be available. Some examples of wood shims include wood wedges, slices, and hinges. It is not a strange concept to pick up pieces of shingles and fashion shims out of available wood in this manner—especially for last-minute needs.


Metal Shims

Metal shims are typically purchased in large stock through companies that can customize orders. They are great in that their simplicity allows for work to be done quickly, but if needed, they can be as complex as the unique shape of an opening or object. With the durability that they can offer, metal shims are often bought first before plastic ones. They are expected to last longer and be more reliable for the job at hand due to their smooth surfaces and more attractive qualities. However, wood shims are equally as competitive in the market because they create friction and are therefore less likely to slip or shift due to side loads.

Differences Based on Application

It is difficult to categorize differences between products as “good” or “bad.” It may make more sense to treat the comparison as a matter of measuring what is needed to what each particular product can deliver. For instance, wood shims may be the ideal solution when you are dealing with other components that are also made of wood. Wooden doors, drawers, chairs, and shelves are a couple of furniture pieces that may be better suited to be leveled or fixed with wood shims. The contact between two wood pieces would be more compatible than trying to close a clearing between metal and wood.

By the same token, if one is trying to find a shim which needs to have certain characteristics—like temperature—then it may be noteworthy to take into account the fact that wood has a lower heat capacity compared to metal. What this means is that it is more favorable to use metal shims with valves in the automotive industry because the heat from the engine should not burn the shim. Whereas, for applications where heat is not a factor, wood is more convenient to saw into. If it is only needed to fill a gap, this would definitely be the more attractive method.


If a designer’s project requires for the shim to be able to withstand a certain amount of stress, then yield strength and pressure should be high on the list of standards to compare materials with. For example, a slab of wood may be able to take on a force of 20 pounds when used as a shim, but over time, it could wear down more quickly than a piece of stainless steel metal with the same dimensions. Thus, now a bookshelf that was level at the time of installing the shim could have become weaker over time due to the added load of more books.

Additionally, when budgets are the topic of conversation, one cannot say that wood is cheaper than metal or vice versa. Customized shims can be costly, but choosing the least expensive solution mainly to save money could cause more money to be spent down the road on rectifying issues that the more affordable shim may create. Phoenix Specialty understands that sometimes this happens, so our team of engineers and machinists are ready when you are to either help you select wisely the first time or to help with a piece that may need more tolerance or adjustments! Our line of shims (https://www.phoenixspecialty.com/products/shims) can be customized to any requirements and manufactured to boast precision.

At the end of the day, it has to be an option that is selected based on the application for the shim.

Differences Based on Properties

With the aforementioned information at hand, it could be tempting to think that there is a way to determine if wood shims or metal shims tend to work best. Yet, this ruling cannot be made, because it all really depends on your circumstances.

The sizeable assortment of woods out there used in design and construction beg the question “how can we decide among the selection out there?” Fortunately (and engineers will agree with this), the list of thermal, chemical, and structural properties of a material can make a world of difference. Most often, wood is a better insulator, while metal is a better conductor. In other words, if a project requires for a shim to be able to allow electricity to flow through, then metal would be the optimal choice. The last thing a manager needs is to encounter electrical issues on top of existing level and gap problems.

Engineering properties are not a force to be reckoned with because they often cannot be changed. Even those which can be manipulated by perfectly selecting dimensions or shapes or superimposing other materials (i.e., using alloys) are going to be harder to work with; their mechanical behavior will be less definite and more unpredictable than had someone chosen only one material. Take advantage of the information already recorded and tested to save a manager the headache of performing additional tests to figure out how a wood or metal shim will perform.


How to Compare

For each individual project, there will come a moment when the engineer or worker must make a decision on material and tolerance, along with dimensions and shape to order or make a shim that will address the challenge before them. This is the reason why quantity and quality are both important factors. When considering wood versus metal shims, figure out what it is that is needed and try to predict long-term results of what will happen if that particular shim is chosen. Determine if it will serve its purpose for the time desired. Determine if it will be easy for someone else to come in and adjust it if something fails. Determine what the risks will be and if they are worth it. Or conversely, determine if they are a red flag that a different shim should be used. Be smart and learn as much as possible about your metal shims AND wood shims before choosing between the two.


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