Reusable unit process life cycle inventory for manufacturing: metal injection molding


Unit process life cycle inventory (UPLCI) is a modeling approach that enables researchers to estimate the energy use and material flow for a unit process. UPLCI models can be reused in characterizing a full manufacturing line, where a wide range of machines and materials are used. As part of a collaborative effort from various universities and industry researchers to create UPLCI models for all common manufacturing processes, this paper presents UPLCI for the metal injection molding (MIM) process, which is in the mass conserving category of the taxonomy of manufacturing processes. In addition to the energy required for injection molding of the metal-polymer feedstock and for the subsequent debinding and sintering processes, the energy consumption during idle and standby periods are also captured. The application of the UPLCI model for MIM process is demonstrated using an example case study. This UPLCI model provides opportunity for researchers to estimate the energy use for a sequence of manufacturing processes used to make a metal injection molded product.

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Coefficient of performance


Life cycle inventory


Metal injection molding


Unit process life cycle inventory

Apart :

Projected area of the part

cj :

Empirical constant

cpm :

Heat capacity of the metal powder

cpi :

Heat capacity of ith binder component

dcl :

Clearance between mold and part

dcav :

Depth of the mold cavity

Eclamping :

Cooling energy consumption

Ecool :

Cooling energy consumption

Einjection :

Cooling energy consumption


Injection molding (IM) energy use

Emat_inj :

Material injection energy consumption

Emelt :

Melting energy consumption

Epack :

Packing energy consumption

Ereset :

Resetting energy consumption

Ebasic(IM) :

Basic energy for IM

Etotal :

Total energy consumption per part

Hcool :

Heat to be removed from the molded part

Hfi :

Heat of fusion for the ith binder component

Hm :

Heat of fusion for the metal powder

hmax :

Maximum wall thickness of the part

Ls :

Maximum clamp stroke of the machine


Mass of feedstock

ncav :

Number of cavities in the mold

pinj :

IM machine injection pressure

Pbasic(IM) :

Basic power of IM machine

Pinj :

IM machine injection power

Qmax :

Maximum material flow rate

Qavg :

Average material flow rate

tbasic(IM) :

Basic IM time

tcycle(IM) :

IM cycle time

tc :

Cooling time

tdry :

Dry time

tdwell :

Dwell time

ti :

Injection time

tr :

Resetting time

Tej :

Ejection temperature

Tamb :

Ambient air temperature

Tm :

Mold temperature

Tinj :

Injection temperature

Vbinder :

Volume of the binder

Vi :

Volume of ith binder component in shot

Vm :

Volume of metal powder in shot

Vpart :

Volume of the part

Vshot :

Volume of the shot

Xb :

Mass fraction of binder

Xm :

Mass fraction of metal powder


Coefficient of thermal expansion


Volumetric shrinkage


Thermal diffusivity of the material

λf :

Thermal conductivity of the feedstock

ηclamp :

Energy efficiency of clamp motor

ηcool :

Energy efficiency of cooling system

ηheater :

Energy efficiency of barrel heater

ηscrew :

Energy efficiency of of screw motor

ρb :

Density of the binder

ρi :

Density of the ith binder component

ρm :

Density of the metal powder


Fraction of part volume in the gating system


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The authors would like to gratefully acknowledge Michael Overcash, Janet Twomey, and Jackie Isaacs for their contributions to developing the unit process life cycle inventory methodology. This material is based upon work supported by the National Science Foundation under Grant no. DUE-1432774 at Oregon State University, as well as Research Seed Fund Project supported by Oregon State University and HP Inc.

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Correspondence to Kamyar Raoufi.

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Raoufi, K., Harper, D.S. & Haapala, K.R. Reusable unit process life cycle inventory for manufacturing: metal injection molding. Prod. Eng. Res. Devel. 14, 707–716 (2020).

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  • Metal injection molding
  • MIM
  • Process energy
  • Unit process
  • Unit process life cycle inventory