Trouble-Shooting Guide for vacuum-formed refractory fiber shapes
Here are some typical problems with vacuum-formed shapes:
• check weight or volume of
starch used
• increase starch in formulation
• clean out system with Clorox to kill bacteria
• treat white water like swimming pool to keep bacteria-free
• thoroughly dry parts before storing
• chop fibers longer or add some chopped fibers to formulation
• consult your fiber supplier
• optimize by using less small-particle-size colloidal in formulation
• use larger-particle-size colloidal silica
• try a different pallet and/or lot number of starch
• check weight and size of filler used
• increase binder level by 10% and monitor forming time
• check weight, size, and quality of filler used
• try a different pallet/lot
• try fiber from a different pallet/lot/bag
• consult with fiber supplier
• check weights and filler analysis
• use coarser filler — 100-120 mesh size preferred
• try 48 or 35 mesh to open it up
• check weights and silica:starch ratio
• reduce starch or Wesil Binder by 10%
• Don't use clays with Wesil Binders
• in general clays like bentonite increase forming time and drying time
• reduce starch to increase silica:starch ratio
• run lower fiber content in slurry
• use less Wesil Binder
• reduce silica:starch ratio in formulation (use less colloidal silica)
• if using Wesil Binder reduce level by 10%
• clay tends to hold water — reduce by 10%
• drying above 250°F degrades starch
• low humidity gives fastest drying
• use more air circulation early in drying cycle
• check to be certain correct amount of colloidal silica was added
• increase colloidal silica by 10% to see if floc improves
• try a different pallet/lot
• if pre-dissolved, make up fresh batch
• use higher-temperature fiber
• use larger particle colloidal silica
• switch to colloidal alumina binder
• use alumina filler
• use mullite filler (with high alumina content)
