Securing small, thin pieces of metal during the milling process can be a big challenge. There are several ways to do it, but which produces the most favorable results?
Mechanical fastening is one option, but it’s often ruled out when the part is so small that it simply does not have enough area to accommodate the fasteners. Using tabs can effectively secure the part during the milling process, but presents a secondary problem – removing the tabs without damaging the finished part. Another common practice is using adhesives such as double-sided tape. However, tape is inherently flexible and frequently allows the part to move during machining, thereby jeopardizing quality.
DATRON has found that using hot glue can be a very effective technique. Here’s how it works:
- Get a stick of high-bond glue like the ones found at a craft store for use in a hot glue gun.
- Cut a piece that is wider than the part that you need to secure and about ¼ inch thick.
- Place that piece of glue on a ridged sheet of aluminum material and heat it in a toaster oven set to 350 degrees.
- Once the glue liquefies, remove the sheet of aluminum from the toaster wearing oven mitts or using tongs, and place the part you need to machine on the liquid glue. (If the part is very thin or light, you may need to press it down using a pencil before the glue sets.)
- Within minutes, the glue will harden and effectively secure the thin metal piece to the aluminum sheet. You are now ready to place the aluminum sheet in a vice and begin milling your part.
- Once you are done milling, reheat the aluminum sheet with your part it in the toaster oven and remove your part when the glue softens. You may find some residue on the finished part which can be removed with a product like Goo-gone. You can also remove the residue by reheating the part one last time and sandwiching it between paper towels.
While the hot glue method detailed above is reserved for extremely small parts, vacuum workholding can be used when milling somewhat larger flat parts or batch milling many parts from sheet material. DATRON vacuum tables are designed to secure flat workpieces from 0.001” to 0.250” within seconds. These vacuum tables feature airflow-optimized ports with recessed chambers to provide superior vacuum distribution. A low cost, gas-permeable substrate serves as a sacrificial vacuum diffuser, allowing the cutter to machine through the workpiece without cutting into the table.