What type of layout is preferred for low volume production of non standard products?

Management costs

For low volume production, the issue of R + D management costs needs to be taken seriously. The specialised nature of the R + D and the fact that subcontracted consultancy companies are invariably used requires clear management direction if any results are to be achieved. Specific management time-costs which can be identified are:

the project manager;

in-house technical specialists – typically, input is required for each of the five main ‘systems’ described previously. Such costs tend to be incurred ‘by department’ within the manufacturer.

3.15.3.1 Hand Layup

For lower volume production runs, hand layup processes are generally the most common option. Typical parts made with these processes include bus body panels such as sidewalls, rear caps, and front masks. With volumes less than 500–800 per year, hand layup can produce a part with acceptable surface finish and structural properties without the need for expensive tooling. However, hand layup manufacturing only produces a good surface finish on one side of the part. The back-side remains rough so this manufacturing method shouldn’t be used for parts that require two good surfaces, such as bus baggage doors. Disadvantages to hand layup processing are potential inconsistency between parts depending on the skill of the personnel. It is also a labor-intensive process that can increase the final part cost. In addition, as an open mold process, it can release volatile organic compounds into the working environment, which calls for more stringent workplace health and safety practices than closed molding processes.

2.10 Summary of chapter outcomes

This chapter distils elementary philosophies of engineering economics with fundamental technical and economic attributes of AM production. Based on this simplified analysis, the following commercially robust opportunities for AM application are identified.

2.1.3 Pentabromoethyl benzene (PBEB or PEB)

PBEB is a low production volume chemical manufactured by Albemarle in France, and used as an additive brominated flame retardant in thermoset polyester resins (circuit boards, textiles, adhesives, wire and cable coatings, polyurethanes) and thermoplastic resins [120]. It is also used in unsaturated polyesters, styrene butadiene copolymers and in other textiles [37]. In United States, PBEB was produced by Dead Sea Bromine Group Ltd. (now ICL Industrial Products) under the trade name FR-105 mainly in the 1970s and 80s [33]. Its production was estimated to be 45–450 tons in 1977, which further declined to 5–225 tons in 1986. However, no US production or import volumes have been reported after 1986. In Europe, its production was estimated to be 10–1000 tons in 2002 [120]. There is no recent information regarding global production and usage, and in fact, it is included in the Oslo-Paris Convention (OSPAR) list of chemicals, being ranked as persistent, liable to be bioaccumulative and toxic, but with no current production [33,37].

2.9.8 Manufacturing Volume

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One-off or relatively low-volume production: Use standard catalogue seal or gasket profiles wherever possible to ensure economic and timely supply and proven design data. FIP sealing with manual application can also be considered.

Regular production of repeat components, several hundred per week: Catalogue seal and gasket profiles will still be economic if they do not compromise the design. Some automation may be considered such as robot-applied FIP or cure in place. Specialist manufacturers may be considered to provide nonstandard profiles.

High-volume production, several thousand per week: Specific seal designs may be considered to optimize the component design and assembly. Seal designs and profiles may be considered specifically for the component. Standard items such as O-rings may be colour coded or surface treated to specification to aid identification and assembly. Moulded-in-place seals may be considered or fully automated FIP or CIP.

Top-Down Cost Assessment Approach

If production costs of fuel cell stacks and batteries for today’s low production volumes are known, this information can be used together with learning curve factors from the literature to derive future costs at higher production volumes.

For a more precise result, this can be carried out separately for individual parts of a fuel cell system or a battery. For example, costs for the membrane in a fuel cell stack today could be combined with a typical learning curve rate known from chemical industry products in order to estimate a future decrease of production costs. On the contrary, values for an air compressor of a fuel cell system could be derived using a more conservative learning curve rate from the segment of mechanical engineering.

Nevertheless, this approach is classified as a top-down type of method as it does not analyze any specific step of production in great detail. To account for uncertainties, calculations can be carried out using several different learning curve factors to reveal possible variations in the results. For an assessment of future production costs of PEMFC stacks, this type of approach has been used for example by H. Tsuchiya and coworkers.

5 Effect of Manufacturing Scale

A major cause of the present high cost of Li-ion batteries for electric drive vehicles is their low production volume. In projecting costs for 2020, we have assumed production levels of 100,000 batteries per year for a fixed design, which allows maximum automation. We have also projected the development of a large Li-ion battery industry with suppliers of electrode materials charging low stable prices that are almost independent of the size of the order by the battery producers. Even with these conditions, we found that changing the production volume from the set level of 100,000 had substantial effects on the price of the batteries to OEMs.

The effects of manufacturing scale come into the cost calculation even if the annual number of packs produced is unchanged, but the design is altered (e.g. energy is increased). These effects are superimposed on the effects of overall production volume. For a fixed design, the effect of changing the scale of operations depends on the fraction of the total price that is made up of materials costs and purchased items. Unit materials costs change little with scale, whereas the costs per pack for labor, capital and plant area may decline substantially with increasing production rates. In Figure 6.13, the cost of materials and purchased items is 46% of the total price for the HEV batteries at 100,000 batteries per year production, but for the PHEV20 and EV130 batteries, these costs are 58% and 70%, respectively, of the total price for that level of production. As the production level increases, the fraction of these costs in the total price increases. Thus, HEV batteries realize a greater benefit from manufacturing scale than EV batteries.

It should be noted that even the battery prices indicated in Figure 6.13 at the low production level of 10,000 batteries per year are lower than those of 2012 because of lower materials prices and the use of a plant designed for that level of production with no special provisions for future expansion. Thus, the reduction in battery prices going forward should be greater than that shown in Figure 6.13, considering cost reduction for materials and plant modifications from current conditions that are not taken into account by Figure 6.13. The continued increase in the scale of battery production from the level of 100,000 batteries per year, which may occur by 2020, to 300,000–500,000 in later years should result in further reduction in their price.

Production Volumes

Another broad and traditional way of characterizing products has to do with long-made distinctions between high-, medium-, and low-volume production quantities—considerations that are best made in relation to the cost of the product, its technical sophistication, and its manufacturing process determinants. Clearly, many common “high-production/low-cost/low-sophistication/intensive-process” products are produced with great economy of scale in huge numbers by strongly deterministic manufacturing processes. The humble stamped pie plate provides an example. In terms of our discussion, these are “process-intensive” end products for which care must be taken in assuring that a competitive advantage would accrue before any even seemingly minor design variations are undertaken. (For example, is there really a market pull for elliptically shaped pie plates made of expensive high-strength nanocomposites as the base material?)

Metals

Machining is the process of removing material with cutting or grinding tools. Many machining operations are automated to some extent, although for low volume production, such as spacecraft manufacturing, manual processes supported by CAD/CAM tools are often cost effective.

Forming is one of the most economical methods of fabrication. The most limiting aspect of designing formed parts is the bend radius, which must be made quite large to limit the amount of plastic strain in the material. Super plastic forming and diffusion bonding, at temperatures up to 1000°C, can produce complex components; however, this process can be used only for titanium alloys because others are prone to surface oxidization that inhibits the diffusion bonding. Spin forming has been applied successfully for manufacturing of aluminum pressure vessels.

Forging, a process in which structural shapes are produced by pressure, is well suited for massive parts, such as load introduction elements. Where large sheets have to be manufactured, such as the skin of main thrust cylinders, chemical milling frequently is used to reduce the thickness of the sheet where possible. This process is more reliable than machining when processing very thin elements; however, tolerances must be sufficient to account for various inaccuracies, such as thickness variations in the original piece of material.

Casting can be used to produce parts of complex shapes. However, the quality of a casting is difficult to control because, as the material solidifies, gas bubbles can form. This results in porosity. Material strength and ductility are not as high as with most other processes.

Abstract:

Terminal sterilisation of sealed packages containing healthcare products, biomaterials and tissue allografts can be the sterilisation method of choice, particularly for expensive, low production volume items such as drug-device products and biomaterials such as bone, skin, tendon and other soft matter used by tissue banks. Validation of sterility to sterility assurance levels of 1:106 is based on a statistical approach and may supplement or replace other methods such as using aseptic control of the production environment. This chapter reviews the current state of the ionising radiation sterilisation protocols and their applications to a wide range of healthcare products and biomaterials.