RP information request

From: Jake Tucker (Battelle Pacific Northwest Laboratories)
Date: Friday, July 22, 1994

From: Jake Tucker (Battelle Pacific Northwest Laboratories)
To: RP-ML
Date: Friday, July 22, 1994
Subject: RP information request
To Whom It May Concern,
     I am currently conducting a "state-of-the-art" analysis of Rapid  Prototyping/Solid Freeform 
Fabrication (RP/SFF) technologies at the Pacific  Northwest Labs (PNL).  (By RP I mean those 
technologies which build-up 3D  objects from CAD solid models in a laminate fashion.)  
     PNL is a DOE lab and has been chartered with using its technology base to  support industry.  PNL has 3 primary interests in pursuing the "state-of-the-  art" in RP:  1) procure current RP technology for 
support of regional  manufacturing; 2) "off-the-shelf" technology infusion into current process  
development efforts; and 3) new process development.  Potential "sponsors  and/or partners" have been identified at each level of interest.  To pursue  these interests, we hope to identify current "gaps" in the technology by  defining the "state-of-the-art" and comparing current capabilities with demands  of future applications.  We are interested in any collaboration which would  speed us along.  In specific, we have identified roughly 19 commercial RP  vendors worldwide and would be interested in collaborating about the  capabilities of these processes (e.g. SLA, SLS, etc.).  If anyone has specific  information concerning the capabilities of any particular RP technology I would  be interested in discussing these matters further.  Below is a list of  parameteres, along with definitions, that we have compiled to compare diferent  RP technologies.  I would especially appreciate any direct information that  addresses these parameters.My e:mail address is:
Thanks,
Jake Tucker
e-mail: jc_tucker@pnl.gov


RAPID PROTOTYPING PARAMETERS
     Rapid prototyping parameters can be grouped into three major categories:
Equipment Parameters
Dimensional Parameters
Material Parameters
     Equipment parameters captures the overall performance of the equipment in terms  of cost, work 
envelop, etc.  Dimensional parameters capture the tolerances,  surface finish, etc. associated with 
fabricated shapes.  Finally, the material  parameters capture material properties.  Parameter definitions are provided in  the following sections.

EQUIPMENT PARAMETER 
1.   BUILD SPEED
     This refers to the speed or rate of shape fabrication.  Two measures are  important here:
     Scan velocity or volume/sec: scan speed x cross section of the voxel geometry  or thickness of material being added to the shape.
     Overall build speed: approximate build-time for a shape nearing the maximum  work envelop of the 
rapid prototyping apparatus.
     The first measure capture the speed of the material deposit cycle.  The second  measure captures this 
time as well as the time between the material deposit  cycle (material preparation time, 
positioning/alignment time, etc.).
EQUIPMENT PARAMETER
2.   COST
     The primary cost is the initial equipment cost.  The next important cost is the  cost of the prototyping 
material by volume.  The third and final cost category  is any information that might provide maintenance 
cost estimates (i.e., are  there service agreements?).
EQUIPMENT PARAMETER
3.   WORK ENVELOP
     This refers to the maximum size of the fabricated shape which the rapid  prototyping process is capable of producing.
EQUIPMENT PARAMETER
4.   SPECIAL TOOLING REQUIREMENTS
     This identifies any special tooling requirements required of the rapid  prototyping process.  One 
example is special supports needed to keep the object from falling over during the build process.
EQUIPMENT PARAMETER
5.   ENERGY REQUIREMENTS
     This is a measure of the energy per unit volume (specific energy or horsepower)  of the material 
produced by the process.  This information seeks to establish  which process is most energy efficient.
EQUIPMENT PARAMETER
6.   EQUIPMENT FOOTPRINT
     This refers to the size of the equipment and support utilities required.  This  information seeks to 
capture how portable the equipment is and how much  infrastructure is required to support it.
EQUIPMENT PARAMETER
7.  ENVIRONMENTAL TOXICITY
     This seeks to capture any information regarding by-products and/or waste streams generated by the 
rapid prototyping process.
EQUIPMENT PARAMETER
8.  RECYCLABILITY/WASTE OF MATERIALS
     This parameter is related to the previous parameter, and seeks to identify if  the raw material can be 
recycled or re-used by the process (e.g., unused powder  can be reused).
EQUIPMENT PARAMETER
9.  DOES IT REQUIRE/PROVIDE MICROSTRUCTURAL CONTROL?
     (YES/NO, IF YES - DESCRIBE)
     This captures if the process can control the microstructure of the shape being  formed.  (e.g., can we 
control grain size in metals, can we control where we  place two different materials inside a single shape, 
etc.)

DIMENSIONAL PARAMETER
1.   DIMENSIONAL ACCURACY
     This is measured by percent accuracy.
          Percent accuracy = tolerance/dimension
It can also be estimated by dividing quoted accuracy by dimensions of work  volume.  This is the hardest 
metric to find.  We may need to ask for accuracies  in the XY plane vs. accuracies in the Z-axis.
DIMENSIONAL PARAMETER
2.   SURFACE FINISH OF PARTS AND ASSOCIATED BUILD PARAMETERS
     This measures the surface finish of the part produced.  As this may vary  according to build speed, 
capturing build parameter information for any given  surface finish is important.
DIMENSIONAL PARAMETER
3.  SECONDARY PROCESSING REQUIREMENTS
     This identifies any secondary processing requirements, such as cleaning,  post-curing, polishing, etc.

MATERIAL PARAMETER 
1.   FABRICATION MATERIAL
     Is the prototyping material a polymer, metal, ceramic, composite, etc.? What  specific material type or 
designation is it?
MATERIAL PARAMETER
2.  MECHANICAL PROPERTIES
     This captures the mechanical properties of the material as measured by the  tensile strength, impact 
strength, Young's modulus, and hardness.
MATERIAL PARAMETER
3.  PART DENSITY
     This applies largely to the powder processes.  Measures include percent base  material versus bonding material, and/or functional density/porosity of the part after debinding and after sintering.
MATERIAL PARAMETER
4.  IS THERE PROPERTY ANISTROPY?
     This seeks to identify if the finished shaped has uniform material properties,  resulting from the 
laminate nature of the particular rapid prototyping process  being used.  Typically, properties (tolerances, mechanical properties, surface  finishes, etc. are worse in the Z-axis vs the XY plane.  Measures for this  include dividing the Z-axis parameter by the value for that parameter in the XY  plane.
MATERIAL PARAMETER
5.  THERMAL PROPERTIES
     This captures the thermal properties of the material in the finished shape.   Thermal measures include 
the melting point, thermal conductivity, and  coefficient of expansion.


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