Subtask 1.1: Target specification document, based on product and market requirements of the end using companies.
This document was presented in Month 3 of the project and is part of the Six Month Periodic Progress Report.
Subtask 1.2.: Description and assessment of a composite toe cap designs and optimised laminate lay-ups.
The description and assessment of the composite toe cap design is also part of the Six Month Periodic Progress Report.
Subtask 1.3.: Description of material behaviour while molding, techniques to avoid wrinkling.
The material behaviour while molding was also part of task 1.3. Process Simulation. A model was developed specifying outstanding parts of the toe cap. The detailed description is part of the Six Month Progress Report.
Subtask 1.4.: List of selected materials (polymer types, fibre types, reinforcement structures).
For the Six Month Progress Report a list of materials that could be used in principle was fixed.
In the end for the tailored blank technique a combination of different materials was examined: As reinforcement glass fibres, aramid fibres, and a combination of glass fibres and polypropylene was used. As matrix system PP, PA 66, and 4 different TPU systems were employed. Finally a combination of glass fibres as reinforcement and Estane (r) X-4890 from BF Goodrich in combination with aramid layers were selected as material for the production of the prototype toe caps.
For the 3D commingled preforms two different yarns were used, namely a 200 tex PETG/glass commingled yarn for the knitted component of the preform and a 1200 tex commingled yarn for insertion into the knit. All the knitted samples supplied had the main load carrying fibres oriented in a unidirectional band running centrally along the length of the fabric roll. Both fibre yarns were based on glass and PETG with a fibre volume fraction of 0.41. PP was also used as matrix system.
Subtask 2.1.: CAE tool design and CNC tooling data, based on the design 701 with modifications.
For the Six Month Progress Report CAE tool design and CNC tooling data was ready. First tools were manufactured based on these data. Later on it turned out that the tooling had to be modified. This was also done on bases of the appropriate tooling data.
Subtask 2.2.: Suitable processing equipment for manufacturing toe cap prototypes.
The processing equipment for first prototype toe caps was ready by month 12 of the project for the organic sheet technology, and by month 18 for the commingled pre-forms. Several modifications of these prototypes were necessary to obtain the best toecaps possible. Up to the end of the project only left handed toe caps were manufactured due to the high costs every modification of the tools caused.
Subtask 3.1.: Basic set of semi-finished materials and specifications on characteristics.
Several material combinations for both techniques were examined and compared due to their appropriateness for the respective application. For the organic sheets technology the following parameters were selected:
* Fibre volume contents should be between 50% and 55.
* No additional aramid layers have to be used.
* Filament glass 300 g/m2 is preferred.
* Random mats and flow core systems are not appropriate.
* TPU has a inherently better impact performance compared to PA 66
For the commingled preforms it was decided to first pre-impregnate the fibres with the resin and then the mould the toe caps. As matrix a GMT (glass mat thermoplastic) was used consisting of the same thermoplast as the resin used for fibre impregnation. During this task woven commingled yarns of PP/glass and PET/glass with a glass content of 50 % by volume wee selected.
Subtask 3.2.: Optimised organic sheet material, basic process parameters for production of organic sheets, basic process parameters for toe cap processing.
During this task the final material for organic sheet technology was selected as being Estane(r) X-4890 delivered by BF Goodrich. The organic sheets were delivered by Bond Laminates. The basic process parameters were fixed. The results of this deliverable are summarized in the Mid Term Report.
Subtask 3.3.: Optimised 3D commingled preforms, NC data for 3D knitting process, basic process parameters for toe cap processing.
It was also examined to use the weft knitting technique for the manufacturing of the commingled preforms since there is the potential of significant increase of mechanical properties by employing this technique. The thickness may be reduced to almost half of the thickness of the commingled fabric/ GMT hybrid. Furthermore little intraply shearing occurs. There are still a few problems with the manufacturing of the final toe caps but these problems will be solved within the next few weeks.
Subtask 3.4.: Testing data.
To improve the double belt processing of the organic sheet technology microscopic examination of the impregnation was carried out. No void entrapment or impregnation defects are visible. Since the materials under investigation first showed signs of thermal degradation (demonstrated by DTMA and DSC measurements), BF Goodrich supplied the finally used material TPU X 4890 which does not show these problems.
For the commingled preforms best results were found for the PETG/glass fibre/ GMT material combination. Due to some problems with processing the performance of the material has not reached the best values possible but has proven that the principle approach of this methodology is worth for further investigations.
Subtask 4.1.: Process specification document about production costs, throughput time, and quality assurance. The goal of this project was to produce the toecaps as cheap as possible to meet the market requirements. Furthermore the process must be able to be scaled-up to produce a volume of 500 000 pairs per year. The process must be industrially robust and reliable enough to provide consistency of performance.
Subtask 4.2.: Prototype processing line for Organic Sheet and Direct Impregnation process.
For both techniques viable processing lines leading to prototype safety caps with the desired properties were designed. The processing parameters were optimised.
Subtask 4.3.: Process parameters of the optimised processes, Delivering of toe caps
When manufacturing the first prototype toe caps it turned out that for the organic sheet technology increased thickness was needed at the front part of the toe caps. Therefore additional sheets were added using the so-called "tailored blank technology".
For the commingled preforms the main objective of this task was to minimise cycle time. Therefore the heating and cooling methods had to be optimised. The same is true for the pressing process.
Subtask 4.4.: Feasibility Study for overmolding of toe caps.
To lower the costs it was examined whether there exists the possibility to produce toe caps from only one single organic sheet and to mould certain reinforcing structures onto the surface of these caps. First trials carried out by Wieser turned out to be successful but testing of the performance did not take place during the project time.
Task 5: Experimental Testing of Toe Caps.
An independent testing institute was subcontracted for testing the toe caps. Toe caps manufactured via the organic sheet technology using the final design selected passed all the tests necessary for the EN 12 568.
The toe caps produced with the commingled preform technology failed only in a single test.
Subtask 6.1.: Prototype safety shoes
Urho Viljanmaa manufactured shoes with the new toe caps. Wieser moulded the soles to the shoes.
Subtask 6.2.: Test report for prototype safety shoes.
Tests are currently underway.
Subtask 6.3.: Cost report, enabling the economic effectiveness.
Up to now composite toe caps manufactured using the organic sheet technology cause production costs of 1.6 Euro per pair. Costs are mainly due to the material costs for the Organic Sheet process.
Due to longer cycle times and the need for more manual work the costs for the Direct Impregnation Process are higher than that for the Organic Sheet process. Further process optimisation and the use of scrap material will help to lower the manufacturing costs.
Subtask 6.4.: Recycling concept.
First trials showed that a viable recycling concept can easily be created helping to reduce the amount of waste from "rejent" toe caps and from toe caps damaged after impact or at the end of their life time. The material re-used was subjected to tensile and flexural testing several times. In summary the material performed well.
The features of protective footwear are defined by the level of security, the comfort and the design. Toe caps are one of the decisive parts of protective footwear having significant influence on these features and on product costs. Toe caps of protective footwear used in working areas with high safety requirements are usually manufactured of sheet steel to provide a combination of stiffness and impact resistance required by the safety standard. Driven by the market, the manufacturers of protective footwear demand a new kind of high performance toe caps to overcome the restrictions of common steel caps. There is a requirement for toe caps showing the following characteristics: - Low weight, - No electric conductivity, - High thermal insulation, - Non magnetic, - Easy shapeability A new toe cap which combines these characteristics will allow the introduction of better products (improved performance, better comfort) into the market for protective footwear and will open up new application areas. But all these characteristics cannot be met with currently existing technology. A feasibility study demonstrated that continuous fibre reinforced thermoplastic composites processed by an innovative technology will give a potential solution. Therefore, the main two objectives of the proposed research project are the development of an innovative high performance thermoplastic composite toe cap and the development of a tailored cost effective manufacturing technology for this toe cap. The main tasks within the technical programme are: - Development of a toe cap design concept by FE methods - Design of tools and processing equipment by process simulation - Development of tailored semi finished materials - Development of cost efficient manufacturing process - Testing on toe caps and optimization of process and product - Application proving in safety shoes The main, direct application of the results of the proposed project will be the production of safety shoes with novel composite toe caps due to the demand of the protective footwear market for lightweight, high performance safety shoes without the technical limitations in application and performance of steel toe caps, with better comfort and at competitive cost. The processing technologies and the product design routes developed will allow application in a wide range of markets. Major application areas besides toe caps will be in markets demanding high performance, lightweight and cost efficient composite components like the growing markets : - for sporting and leisure goods, - for working protectors, - for automotive or aerospace components and - for medical appliance. The project will contribute to more safety in European working areas and will contribute to make working live more comfortable. The process technology developed by the project will give a clean, kind and safe environment for fabrication of products. In addition, social benefits of the technology are also significant: Shoe manufacturing capacities have been transferred to Far East, North Africa and South America due to lower cost in these regions. The development of innovative products and innovative processing technologies represents a promising opportunity for European SMEs to compete with these regions.
Funding SchemeCRS - Cooperative research contracts
LE13 0PB Melton Mowbray - Leicestershire
61280 Jalas Järvi
78570 Mühlheim - Donau