If your melt index values are either too high or too low when you compare your results with suppliers/customers, here is a shortlist of items to investigate to rule out the obvious:

2. Is the machine level?

Any melt indexer machine must be levelled properly before use. We supply a piston level with each machine and this should be placed on the top of the piston to ensure the piston, and barrel, is perfectly vertical; if these aren't vertical the piston could potentially get stuck in the barrel and give erroneous melt index results.