Search results

This paper aims to investigate the applicability of 3D-printed molds to be used as a substitute for photolithography in the formation of polymer-based stamps. It proposes leveraging 3D printing as a rapid prototyping tool to be applied to microfluidic fabrication.

Different designs are created using computer-aided design (CAD) software and printed via Makerbot 3D printer. The molds serve as negative reliefs for a PDMS stamp. The stamp is used to apply paraffin wax to chromatography paper, creating hydrophobic barriers and hydrophilic channels. The minimum functional channel widths and barrier widths are determined for the method.

The method is demonstrated to be effective for bypassing the more cost-prohibitive photolithography approach for rapid paper microdevice fabrication. This approach produces functional channels that can be used for on-chip analytical assays. The minimum functional barrier widths and minimum functional channel widths are in good agreement with other published methods for paper-based microchannel fabrication.

The approach cannot generate the high-resolution structures possible with photolithography. Therefore, if higher resolutions are needed for a particular application, this approach is not the best.

The simplicity of the approach introduces an affordable method to create disposable devices that can be used at the point of testing.

The paper satisfies a need for inexpensive, rapid prototyping of paper-based devices. The method is simple and can be used as a tool for introducing labs to microfluidics research.

Fabrication of customized products in low volume through conventional manufacturing incurs a high cost, longer processing time and huge material waste. Hence, the concept of additive manufacturing (AM) comes into existence and fused deposition modelling (FDM), is at the forefront of researches related to polymer-based additive manufacturing. The purpose of this paper is to summarize the research works carried on the applications of FDM.

In the present paper, an extensive review has been performed related to major application areas (such as a sensor, shielding, scaffolding, drug delivery devices, microfluidic devices, rapid tooling, four-dimensional printing, automotive and aerospace, prosthetics and orthosis, fashion and architecture) where FDM has been tested. Finally, a roadmap for future research work in the FDM application has been discussed. As an example for future research scope, a case study on the usage of FDM printed ABS-carbon black composite for solvent sensing is demonstrated.

The printability of composite filament through FDM enhanced its application range. Sensors developed using FDM incurs a low cost and produces a result comparable to those conventional techniques. EMI shielding manufactured by FDM is light and non-oxidative. Biodegradable and biocompatible scaffolds of complex shapes are possible to manufacture by FDM. Further, FDM enables the fabrication of on-demand and customized prosthetics and orthosis. Tooling time and cost involved in the manufacturing of low volume customized products are reduced by FDM based rapid tooling technique. Results of the solvent sensing case study indicate that three-dimensional printed conductive polymer composites can sense different solvents. The sensors with a lower thickness (0.6 mm) exhibit better sensitivity.

This paper outlines the capabilities of FDM and provides information to the user about the different applications possible with FDM.

“UNDER the clock at Charing Cross Station at 8.30 p.m.” So ran our instructions for Thursday, April 13th. The weather for a fortnight past had brought snow, a wind that was nipping and eager, and weather prophets were not sanguine. One London periodical indeed had burst out with a quotation from Browning adapted to the circumstances:

While the literature has emphasized the literal and the narrative within organizations, this article will consider the visual and the imaginal. Organizations are known and experienced through images, and these images must be considered if organizational culture is to be understood or changed. We look at the imaginal inventory provided by classical mythology, with special reference to Ovid’s Metamorphoses, and explore the potency and persistence of myth in imaginal terms and introduce the concept of the “voice of the shuttle”, which imprints events within the metaphorical weave of the mythical narrative. This “voice”, always present in organizations, leaves significant and revealing images on the cultural fabric. We try to understand these images through the experiences of an organizational participant and of students trying to make sense of their college culture.

We have received a communication from Mr. A. H. Mitchell Muter, F.I.C., Public Analyst for Lambeth, with reference to the contamination of cheese as the result of it being wrapped in tinfoil.—Mr. Muter observes that the following facts are those upon which he based his remarks, re the potential danger to health arising from contamination by tin in cheese wrapped in this metal, contained in his report for the fourth quarter of 1929 to one of the Local Authorities for which he acts :—On 4th November, 1929, a Food Inspector to the Authority in question submitted an informal sample of wrapped cheese as the result of a complaint having been received from a ratepayer to the effect that he had been taken ill after partaking of it.—Mr. Muter's analysis showed it to contain 5·68 grains of tin per lb., and he therefore reported that he was of opinion that the ratepayer was fully justified in bringing the matter to the notice of the Inspector.—On 15th November a formal sample of wrapped cheese was submitted, which he found contained 6·89 grs. tin per lb., and he issued a report to this effect. As the result of this report he received on the 25th November five informal samples of various brands, all of which were found to contain tin varying from 0·28 to 6·34 grs. per lb., and a further three informal samples received on the 3rd December contained tin in quantities from 1·37 to 11·03 grs. per lb. On the 12th December a formal sample was submitted which contained as much as 14·8 grs. tin per lb.

The purpose of this paper is to present the development of a technical procedure for the manufacturing of medical implant prototypes.

The paper was performed on a new hip implant design and manufactured with different metallic alloys F75 (ASTM) commonly used in biomedical applications. Dimensional parameters between the computer‐aided design (CAD) geometry and the prototypes and surface roughness for different casting alloy were compared. A CAD model was used for machining of a prototype. Room temperature vulcanising (RTV) rubber moulds allowed the manufacturing of wax models of the femoral prosthesis. A specific lost‐wax casting (LWC) technology was used to manufacture prototypes for in vitro tests. The final geometry was dimensionally controlled using different type of parameters (performance, average, standard, maximum and minimum deviations), surface roughness (Ra, Rt and Rp) were measured for all prototypes.

To obtain a small number of implants, RTV rubber vacuum casting technique can be used to obtain lost wax models with good dimensional stability. No significant dimensional differences were observed relatively to the virtual model. However, the temperature of the wax and the rubber mould were important parameters to obtain good quality wax models. Surface roughness was different for different alloys.

The design and development of a new hip femoral prosthesis prototype based on rapid tooling techniques to manufacture LWC prototypes is suitable for clinical trials.

This paper describes a biomanufacturing methodology to manufacture biomedical implant prototypes.

A pine/co-PES composite (PCPES composite) was proposed as the feedstock for powder bed fusion (laser sintering, LS). This paper aims to provide some necessary experimental data and the theoretical foundation for LS of pine/co-PES, especially for the application of using the laser-sintered pine/co-PES parts as complex structural patterns in investment casting.

The PCPES composites with different pine loadings were mixed mechanically. The composite’s preheating temperature and processing temperature during LS were determined experimentally based on the material’s thermal behavior. The effects of pine powder on the binding mechanism of PCPES composites were discussed through analyzing the microstructure of the laser-sintered parts’. Mechanical properties and dimensional precision of laser-sintered PCPES parts in different pine loadings were tested, and the parts’ mechanical properties were strengthened by wax-infiltration post-processing. The influence extents of process parameters on the mechanical properties of laser-sintered 20 Wt.% pine/co-PES parts were investigated using a 1/2 fractional factorials experiment.

20 Wt.% pine/co-PES is considered to be a promising wood-plastic composite for laser sintering. The relationship between mechanical strength of its laser-sintered parts and process parameters was built up using mathematical formulas. Experimental results show density, tensile strength, flexural strength and surface roughness of laser-sintered 20 Wt.% pine/co-PES parts are improved by 72.7-75.0%, 21.9-111.3%, 26.8-86.2%, 27.0-29.1% after post-process infiltration with a wax. A promising application of the wax-infiltrated laser-sintered parts is for investment casting cores and patterns.

The proper process parameters and forming properties of laser-sintered parts are limited to the results of laser sintering experiments carried on using AFS 360 rapid prototyping device.

This investigation not only provides a new feedstock for laser sintering with the advantages of low cost and fabricability but also uses an advanced technique to produce personalized wood-plastic parts efficiently. Mathematical models between mechanical properties of laser-sintered PCPES parts and LS process parameters will guide the further LS experiments using the 20 Wt.% pine/co-PES composite. Besides, the laser-sintered PCPES parts after wax-infiltration post-processing are promising as complex structural patterns for use in investment casting.

In considering this subject, it is desirable to consult, and to go by, official documents and any comments made thereon by competent and unprejudiced persons who are recognised as authorities in their special line. In this connection it will be best to take, first, the text of the latest Imperial law as it stands (which is very explicit in regard to what is permitted and to what is not permitted to be done), secondly, the still more explicit official instructions as to how this law is to be carried out and enforced, and, thirdly, the comments of experts on the subject in some standard book intended for public guidance. Such a book is No. 68 of the well‐known Guttentag Law Series, edited by Doctors Lebbin and Baum.

1. Buxton, Bonnie and Betty Guernsey. Montreal Inside Out. Enl. and rev. Ottawa, Wax Wing; distr. by Burns and MacEachern, 1976. 282pp. $3.95 paper. ISBN 0‐919988‐01‐6. The first edition was in 1974, at the same price, but printed on the worst sort of paper imaginable. Buxton and Guernsey at that time merely reprinted their Montreal Gazette columns. This current work, while it has adapted much of the same material, is now a better book for outsiders. Hotels and tourist homes have been added; the restaurant section, while redesigned from expensive to budget (it was formerly “budget to expensive”), still is non‐critical; and purely local references have been deleted, such as “the great Montreal sausage hunt.” As I really love sausages, I simply decided to rip out those particular pages for adding to the second edition. Also odd as it may seem, the YWCA between 1974 and 1976 apparently eliminated its “free” women's toilet (there is no mention of it here), while the YMCA boosted its facilities — probably too many ladies used the john. The book now begins with a general overview that proceeds through the usual guidance of selecting room and board, things to do and to see, entertainment and sports, fashions, shopping, buying food (breads, candy, patisseries, fish, markets, etc.), day trips off the island, and the vital “services, emergencies, and repairs.” Its companion volume is Great Montreal Walks (1976) — both produced in time for the Olympics, but of course current for a few years afterwards.

IN A PAPER PRESENTED TO THE 12TH Annual Meeting of the American Society of Lubrication Engineers in April, at Detroit, Leon Salz of the Magnus Chemical Company described the components and functions of press drawing lubricants. He referred to the highly competitive market among stamping and deep drawing plants that require overall production costs to be carefully calculated, and certainly this is very similar in this country. He said, “A miscalculation with respect to the difficulties that can be experienced in a drawing operation may nullify the anticipated profit. Not uncommon is the shop that submits a bid on the basis of experimental trial runs, only to find that serious problems arise in mass production”.