Model Makers Research Articles

Effect of slice thickness on the profile accuracy of model maker rapid prototyping measured by a circular triangulation laser probe

The objective of this research is to investigate the effect of slice thickness on the profile accuracy of the model maker (MM) rapid prototyping (RP) system, layer by layer, through non-contact laser probe measurement. A circular triangulation laser probe, model OTM-3A20, made by Wolf & Beck Co., was mounted on a coordinate measuring machine (CMM), as the non-contact sensor. An adjustment device for the laser probe was designed to minimise the cosine error caused by assembly inaccuracy. The alignment test of the measuring laser beam was carried out using a calibrated specimen. The systematic accuracy of the circular triangulation laser probe with respect to the surface roughness and the surface slope of the RP workpiece was investigated using a HP5529A laser interferometer system. The maximum error of 21/2D RP part profile accuracy can be improved from 220 μm to 131 μm, and the average error can be improved from 78 μm to 46 μm as the slice thickness changed from 0.127 mm (0.005 in.) to 0.0127 μm (0.0005 in). However, the machining time increases by about seven fold based on the experimental results. An overall error of 197 μm as measured by the laser probe is attainable using the finest slice thickness 0.0127 mm (0.0005 in.) for the 3D profile accuracy. To verify the accuracy of non-contact laser probe measurement, the 3D profile of the RP part was also measured by a CNC CMM, with good consistency.

Database resources of the National Center for Biotechnology.

In addition to maintaining the GenBank(R) nucleic acid sequence database, the National Center for Biotechnology Information (NCBI) provides data analysis and retrieval resources for the data in GenBank and other biological data made available through NCBI's Web site. NCBI resources include Entrez, PubMed, PubMed Central (PMC), LocusLink, the NCBITaxonomy Browser, BLAST, BLAST Link (BLink), Electronic PCR (e-PCR), Open Reading Frame (ORF) Finder, References Sequence (RefSeq), UniGene, HomoloGene, ProtEST, Database of Single Nucleotide Polymorphisms (dbSNP), Human/Mouse Homology Map, Cancer Chromosome Aberration Project (CCAP), Entrez Genomes and related tools, the Map Viewer, Model Maker (MM), Evidence Viewer (EV), Clusters of Orthologous Groups (COGs) database, Retroviral Genotyping Tools, SAGEmap, Gene Expression Omnibus (GEO), Online Mendelian Inheritance in Man (OMIM), the Molecular Modeling Database (MMDB), the Conserved Domain Database (CDD), and the Conserved Domain Architecture Retrieval Tool (CDART). Augmenting many of the Web applications are custom implementations of the BLAST program optimized to search specialized data sets. All of the resources can be accessed through the NCBI home page at: http://www.ncbi.nlm.nih.gov.

On Line Model Accuracy Inspection of Model Maker Rapid Prototyping Using Vision Technology

The principle of rapid prototyping (RP, or layer manufacturing) is to fabricate a 3D object layer by layer. Vision technology has been employed and has demonstrated its ability to measure the single-layer profile dimensions of the Model Maker (MM) RP system model. The on-line profile dimensional inspection and accuracy analysis of multiple layers is presented in this paper. The image-processing algorithms, developed to measure the layer profile dimensions, were adapted to process the captured profiled image of multiple layers, layer by layer. Hence, the layer profile dimensions of multiple layers were inspected on-line and layer by layer. The problems of vision inspection associated with colour mixing of multiple layers are addressed. A colour CCD camera was employed to resolve the colour mixture problem, but it is too expensive and too much memory is required. A new image difference algorithm was proposed to solve the problem of colour reflected from adjacent layers. The results demonstrate the promise of on-line profile dimensions inspection and accuracy analysis using vision technology.

The Application of the Skipped Layer Interior Method and Higher Depostition Height to Accelerate Fabrication Speed of the Model Maker Rapid Prototyping System

The Model Maker (MM) process is one of the jet deposition rapid prototyping (RP) systems that delivers material through a jet and deposits the liquefied material onto a platform to build a physical model. The fabrication speed of the MM model is extremely low because of the low deposition rate and cutting operation. In order to accelerate the fabrication speed of the MM, the line pitch of the MM processing parameters was reconfigured to increase the deposition rate and, hence, increase the deposition height. The cutting operation of the MM removes almost half of the deposited material because of the requirements of model accuracy and layer thickness. In order to reduce the amount of the removed material, a skipped layer interior method was employed. The reconfiguration of the line pitch to increase deposition height enabled more interior layers to be skipped and, hence, less deposited material was removed. Therefore, the fabrication speed was significantly accelerated. The results show that the average model printing time saved was around 40% for all layer thicknesses, while the model accuracy and the layer thickness were still the same as in the original MM process.

On-Line Layer Profile Dimensions Measurement of Model Maker Rapid Prototyping Using Vision Technology

The key principle of rapid prototyping (RP) is to fabricate a 3D object, layer by layer, which is a 2D fabrication process, Vision technology is being successfully applied in general industry to inspect object dimensions on-line, but most of the applications are limited to objects with 2D patterns. Hence, it should be possible to apply vision technology to inspect RP layer profile dimensions on-line. A CCD camera was employed to capture the layer profile image of the Model Maker (MM) RP system layer by layer. The captured image was processed to identify the RP profiles and further to calculate the real profile dimensions of the fabricated layer. The experimental results demonstrate that the dimensions of an RP part could be measured in situ, layer by layer, and could, potentially, be real-time monitored. This paper presents the vision calibration and the detailed image processing algorithms for the single layer profile identification and dimensions measurement. The results show that the measurement accuracy of the layer profile was about 98%.

A new flexible layer fabrication method for the jet deposition system to accelerate fabrication speed

The key principle of the jet deposition rapid prototyping (RP) system is to deliver material through a jet and deposit the liquefied material onto a platform to build a physical model. Model Maker (MM) RP system is one of the jet deposition processes with the smallest slice thickness and better model accuracy. In order to maintain thinner layer thickness and model accuracy, a cutter is employed to plane off the deposited surface. The fabrication speed for MM models is extremely low because of the employment of the tiny jet and the cutting operation. The model interior filling does not affect the model accuracy very much but it does significantly affect the fabrication speed. Hence, a new flexible layer fabrication method is proposed in this paper to separate the fabrication processes of the profile and the interior, respectively, in order to maintain model accuracy and thinner slice thickness, and to accelerate the fabrication speed.

Fast interior filling of Model Maker models using a spraying nozzle to accelerate build speed

Model Maker (MM) is a commercial rapid prototyping (RP) system using tiny jets to deposit thermoplastic materials onto a platform to build physical models and the associated support structures. Also, a cutter is employed to plane off the deposited surface in order to maintain smaller layer thickness and hence, model accuracy. The model’s accuracy is mainly affected by the profile layer thickness. The interior filling does not affect the model accuracy or layer thickness very much, but it significantly affects the building time. Hence, a new interior fast filling of MM using a spraying nozzle is proposed in this paper. The detail design, construction, and evaluation of the new proposed fast interior‐spraying process are presented. The results show that the building time using spaying nozzle is only 15 per cent of the time used by the original process.