Mar 29th 2021
Welcome back to our three-part series on keeping safe while working with carbon fiber & composites. In our second installment we’ll be taking a look at Demold & Mold Prep Safety.
Demold and mold prep safety is much like that of plycut and layup precautions. Keeping working areas clean, using cut-resistant gloves, and wearing proper eye protection are all needed to demold or strip cured laminates. During demold processes, it is not the scissors or blade surfaces that could necessarily cause possible damage to fingers or skin. A cured laminate, whether fiberglass, Kevlar, or carbon fiber, is sharp along laminate edges. Thinner parts of the laminate's corners and cut ply edges all pose a risk of slicing through skin and flesh. Fabrication with chopped strand mat fiberglass also poses a risk as the fibers do not always carry uniformity; there are possibilities that fiberglass fibers could be sticking straight up out of the laminate. If the skin is not protected, it can go through the skin with little to no force. Always wear proper eye protection as chips and resin bleed out can be expected, and pieces can fly into the eyes.
Once the part is stripped or de-molded, de-flashing the part as soon as possible is good practice. Using a right-angle sander and ~220 grit sandpaper, sand away any sharp edges on the composite laminate; this will make handling of the composite laminate much easier in the future.
Personal safety is of the utmost importance in any process; however, part safety of a cured laminate is also vital as some composite parts can be highly fragile. Dropping some parts from only 3 feet has been known to scrap laminates. Gravity tends to aid in dropping objects or chemicals onto laminates. Wrapping parts completely or around edges with bubble wrap will mitigate the chances of damage. The best practice is keeping parts wrapped in bubble wrap when not used while being transported or stored. Additional options include the application of a pool noodle or polyethylene foam noodles around part edges.
Once a part is de-flashed and stored correctly in bubble wrap, mold preparation will likely begin. Using a shop vac will help get a mold cleaned of any loose resin and fabric that may have gotten loose on the tool's surface. Afterward, application of a cleaning agent and/or mold release is needed. Hazards associated with mold releases are corrosiveness and flammability. Though some mold releases are neither, product safety must be adhered to per the product's SDS. If mold cleaner/release cleaner is flammable, proper storage at room temperature in a well-ventilated area, along with keeping it away from any ignition sources, is a must. It is best practice to keep flammable mold releases in their own designated cabinet area, away from other flammable liquids or ignition sources. Always refer to the product's SDS for all safety-related issues ensuring all proper care is taken. Chemically protective gloves are best when applying any release agent.