melt-blowing

design and prototyping of a FabLab-able polypropylene melt blowing setup for distributed manufacture of filter media

challenges

• primary air
  • hundreds of SCFM, 200+ C, ??? psig
• tooling
• process control
  • various temperatures
  • air flow
  • feedstock extrusion
• safety
  • 200 C + pipes and tooling: burn hazard
  • Mach 0.5+ air: loud!
  • fibers: Class III/Div 1 explosion hazard?
• feedstock
  • recycled? pelletized virgin PP?
  • heat + extrude + pump?

literature

• dimensional analysis of process and discussion of nozzle types (1988): https://pubs.acs.org/doi/pdf/10.1021/ie00084a021
• Exxon patent showing slot-style melt blowing nozzle: https://patents.google.com/patent/US3849241A/en?oq=3%2c849%2c241
• UTenn study on melt blowing: https://onlinelibrary.wiley.com/doi/epdf/10.1002/pen.760302202
• good discussion of primary air system requirements: http://jmppnet.com/journals/jmpp/Vol_3_No_1_June_2015/9.pdf

melt blowing videos

• video of a polypropylene filter melt blowing line in action: https://www.youtube.com/watch?v=cGQ4piMNQ_E
• fast construction of a melt blowing line for covid-19 masks: https://www.youtube.com/watch?v=p9lchhBE7cE
• a smaller line with a built-in rotary mask die cutter: https://www.youtube.com/watch?v=KgWHNQo7j1k
• pilot-scale melt blowing machine making a mess: https://www.youtube.com/watch?v=SOFfpGnMjOc