Search results

Polymer rapid tooling (PRT) inserts can be used as injection moulding (IM) cavities for prototyping and low volume production but lack the robustness of metal inserts. Metal inserts can withstand high injection pressure and temperature required, whereas PRT inserts may fail under similar parameters. The current method of parameter setting starts with using the highest pressure setting on the machine and then fine-tuning to optimize the process parameters. This method needs modification, as high injection pressures and temperatures can damage the PRT inserts. There is a need for a methodical process to determine the upper limits of moulding parameters that can be used without damaging the PRT inserts.

A case study analysis was performed to investigate the causes of failure in a PRT insert. From this, a candidate set-up process was developed to avoid start-up failure and possibly prolong tool life. This was then tested on a second mould, which successfully avoided start-up failure and moulded 54 parts before becoming unusable due to safety issues.

Process parameters that are critical for tool life are identified as mould temperature, injection pressure, injection speed, hold pressure and cooling time.

This paper presents a novel method for setting IM process parameters for PRT inserts. This has the potential to prevent failure at start up when using PRT inserts and possibly extend the operating life of the PRT inserts.

THIS is the month when librarians and library workers everywhere, their holidays over, turn to their winter plans. There are, however, some interesting events to take place before the darker and more active months come. The first is the meeting at Oxford on September 21st and subsequent days of the Federation International de Documentation. This will be followed by and merge into the ASLIB Conference, and there is in prospect an attendance of over three hundred. Our readers know that this organization produces and advocates the International Decimal Classification. It is not primarily a “library” society but rather one of abstractors and indexers of material, but it is closely akin, and we hope that English librarianship will be well represented. Then there is a quite important joint‐conference at Lincoln of the Northern Branches of the Library Association on September 30th— October 3rd, which we see is to be opened by the President of the Library Association. Finally the London and Home Counties Branch are to confer at Folkestone from October 14th to 16th, and here, the programme includes Messrs. Jast, Savage, McColvin, Wilks, Carter, and the President will also attend. There are other meetings, and if the question is asked: do not librarians have too many meetings ? we suppose the answer to be that the Association is now so large that local conferences become desirable. One suggestion, that has frequently been made, we repeat. The Library Association should delegate a certain definite problem to each of its branches, asking for a report. These reports should form the basis of the Annual Conference. It is worthy of more consideration.

The case of food poisoning which affected some 150 persons at Derby appears to be undoubtedly a genuine case of ptomaine poisoning. During the last few years many isolated deaths have occurred, after the consumption of some particular kind of food, which have been attributed to ptomaine poisoning, but the evidence put forward in support of this view has not unfrequently been open to grave doubt. At Derby, however, the nature of the outbreak and the symptoms presented by the patients were characteristic, and if further proof were needed it would be contributed by the interim report of Dr. SHERIDAN DELEPINE, of Manchester, who made an examination of the suspected pies and their ingredients. Most people are fully acquainted with the history of this out break, which was not confined to Derby but extended to various parts of the country, in every case the persons attacked having consumed portions of the infected pork pies. Dr. DELEPINE has issued an interim report in which he states that he has isolated a bacillus belonging to the colon group which is, in his opinion, undoubtedly responsible for the pathogenic properties of the pies. The evidence as to the relation of the bacillus to the epidemic is, says Dr. DELEPINE, absolutely clear. The bacillus in question has been isolated from a pork pie, from a pork bone pie, from the blood, spleen and intestines of one of the persons who died, and from the blood, spleen, bile and intestines of several animals which have died in two or three days from the effects of feeding on a pork pie. The bacilli obtained from all these sources were identical in appearance. Animals inoculated with this bacillus have died, and in their blood the same bacillus has been again found; and four specimens of blood obtained from patients who had been ill after eating a portion of a pork pie have given, on examination, a clear serum reaction, but the blood of normal persons and also of patients affected with typhoid fever has given no similar clear serum reaction. Dr. DELEPINE has also been able to ascertain the presence of the same bacillus in a pork pie which Dr. ROBERTSON, of Sheffield, had sent him. This statement appears to leave no room for doubt as to the dangerous nature of the pies, and Dr. DELEPINE's complete report will be awaited with considerable interest.