By Martin Spencer, UniqueRoto
So far in this series we have looked at how understanding a product, building a team of experts to design and develop that product, and pushing the boundaries of the market and process to come together to provide the design for a successful product.
The next step in the process is to procure a tool. Whether this is to be an in-house steel tool or an outsourced CNC aluminium tool – if the product is to look good and be economic as possible to produce – this needs to be the best quality tool the product can justify. A cheap, poor tool produces cheap looking, poor products. This then tends to affect the attitude of the operators in that if the product does not look good when it comes out of the mould they are less likely to take care with that product and unlikely to take pride in the way it is finished and presented to the customer.
During the design process you will have discussed and made decisions on the positioning the parting lines. Now you will need to decide on the way the tool will be mounted on the arm and the order in which the various parts of the tool will come apart.
How will these parts be held together – bolts or clamps positions and operation of flange dowels – will the tool have a frame for handling and protection? If the tool is multi-part what will happen to those parts during the mould servicing process? Tool sections are easily damaged if dropped or handled inappropriately during servicing. I have been involved with many multi-part tools, up to 30 separate sections on some tools, and have experienced flange damage due to careless handling and contamination as sections are placed on the floor or dirty benches, lost, or insert holders were damaged, etc. With modern techniques the tools can be designed so that only one major section comes away and this can usually remain on the crane hook whilst servicing. The other sections can be mounted on hinges or sliders so that they can be withdrawn far enough for demoulding but remain attached to the main tool on the arm. If this not possible then brackets or hooks can be provided on the tool frame for small sections and inserts to be placed and remain during the servicing process.
Small details can save time and aggravation and improve product quality. Placing an insulating sleeve of PTFE or PEEK around breathers will extend the life of PTFE and silicon breathers and helps ensure they stay clear during the moulding process. Using copper, brass, or bronze for inserts and insert holders aids heat transmission and improves material coverage of inserts. Using airmovers/venturies or heat pipes to take heat to difficult areas removes the need for
pre-heating and improves product quality. If (as you should be at least some of the time) you are using thermocouples to monitor internal temperature, then use robust methods of insertion or attachment so that it is easy for the operators and expensive thermocouples do not get damaged. Another great tip to help preserve moulds is to paint all clamps, bolts, and insert holders in a bright heat proof paint so they are easily seen and moulds are not pulled apart with some fixing still in place.
Modern pneumatics are now available that can give a high degree of automation to the servicing process. Multiple tools can be mounted on the spider that all clamp and unclamp together in one operation with the connection of compressed air. This allows the top half of all the tools to be removed together in one crane operation whilst the products are removed and the fixed part of the tool is to be serviced. Careful design of flanges and framework is important so that is does not hinder the rapid heating and cooling of the tools as this leads to long inefficient cycles.
This attention to tool design can considerably reduce the time taken to service whilst preserving the finish and flanges of the tool. This makes for an easier life for the operator produces better parts and they can then take pride in leading to much higher customer satisfaction.
I am sure you are thinking that either your customer or your finance director will object to paying more than the bare minimum for the tool. However, if you look at alternate product costings, considering the cheapest tool – higher scrap rates higher labour costs, lower part quality, operator and customer dissatisfaction will result. Then compare this with a higher tool cost, efficient cycles, fast demoulding, longer tool life, and an overall higher quality leading to satisfied customers. The economics are invariably in favour of spending more on the tool for a lower part cost.
This price equation also applies to the price difference between fabricated sheet metal tools, cast aluminium tools, and CNC aluminium tools. The customer of a consumer type product will usually see the benefits in finish and appearance of a CNC aluminium tool against product produced from fabricated or cast tools. Whilst the customer of an engineering part will see the benefits to accuracy, tolerances, and repeatability that a CNC tool can provide compared to the other tooling types. However, some products, for example those that are very large or that are to be buried underground, do not justify CNC tooling, but they will however benefit from spending a little more time and money on ensuring that they are as user friendly for fast cycles and operator servicing. This will always pay benefits in tooling life and product quality.
Once you have invested in good quality, well thought out tooling, then it needs to be maintained well. Correct minor damage and problems as soon as they occur so that they do not develop into major problems and cause quality problems and scrap.
If you provide operators with good easy to use tools for the task you are asking of them, they will usually respect that investment and take pride in their work producing good looking high quality
parts.
from an article at RotoWorld®
https://rotoworldmag.com/tooling-to-facilitate-production/
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