Common Quality Defects and Causes in Vacuum Formed Products
Currently, vacuum-formed rubber can be used in composite shaping for cabinets, paint-free doors, computer desks, soundboards, and more. Through the vacuum forming process, the surface decoration of board-structured wooden products has transitioned from flat to three-dimensional, especially altering the straight edges and predominantly flat styles of board furniture. However, issues like weak adhesion, blurred decorative patterns, and PVC film punctures persist during the vacuum forming process. What are the causes of these problems? Below, we'll discuss what should be done during vacuum molding to avoid these issues.
Weak adhesion resulting in extensive PVC film detachment from the surface of the workpiece is primarily caused by low heating, inherent issues in vacuum forming, quality problems, expiration, or insufficient resting time after gluing.
Blurred decorative patterns, unclear lines, uneven edges, and corners are caused by excessively intricate linear designs or small dimensions, low heating temperature, or insufficient heating time.
Raised corners where local PVC film detaches from the edges of the workpiece are primarily due to low heating temperature or short heating time, inadequate glue sprayed on the edges, excessively thin work mat, uneven glue spraying, and workpieces being too close together.
PVC film punctures leading to localized perforations exposing the substrate are caused by excessively high heating temperature or prolonged heating time, or when the PVC film is too thin.
Workpiece surface irregularities and roughness post-vacuum forming are mainly due to low glue spraying gas flow, unclean rough blanks, impurities not filtered before vacuum forming, or oversized nozzle on the spraying gun.
Requirements for trimming after vacuum forming:
Workpieces processed by the press need to rest for 20 minutes before trimming (ensuring initial curing of the glue). After trimming, use specialized tools to trim or sand the edges with 120#-180# sandpaper, ensuring the PVC is below the workpiece surface. Clean the backside glue marks with a diluent like alcohol. Inspect quality during trimming; repair where possible, separate items that cannot be repaired for special treatment.
Place vacuum-formed workpieces face to face, back to back, on a flat rack with stacks of 50 pieces, applying weight on top to prevent deformation. Minimum resting time should not be less than 24 hours. Film pressing on the workpiece during mid-term curing is 24 hours; complete curing requires 7 days. Therefore, ensure a minimum 24-hour placement before packaging.
When quality issues arise, adjust processes or parameters step by step while recording changes. Avoid simultaneous adjustments of multiple process parameters, as it will make identifying the actual cause of quality issues difficult. Simultaneous adjustments also make it challenging to establish and adjust production environment standards objectively. Hopefully, the above content will be helpful.
