Financial Summary

Financial Summary:

The crane design has been broken down into many sections which either perform specific roles or group together parts which will be sub-contracted through different sources and companies for efficient logistical operation and to ensure costs are saved by mass purchase.

We will now break down the financial summary into the following stages to build a picture of costing considerations used:

·         Part Costing

·         Crane Kit Costing

·         Sub-Contracts

·         Further Considerations

Pricing of Parts

Below is the cost breakdown of all of the crane components. Each component is priced per unit and all components are made from 7075T6 Aluminium unless stated:

Top Section

·         I Beam – h=135mm   w=150mm  5000mm                                                             £214.51                                 www.aluminiumwarehouse.co.uk

Side Sections

·         Side Section – 150mm x 150mm x 3mm                                                                  £155.52                                 www.aluminiumwarehouse.co.uk

·         Corner Joint – Each unit would require 2 lots of the following:

-          2 channel extrusions (C – Shaped)   4 x £11.46 = £45.84

-          1  7075T6 Al Sheet                                    2 x £2.09 = £4.18              

-          Fabrication Cost                                                        £80                         £130.02

        www.aluminiumwarehouse.co.uk

Quad pods

·         Foot Holders – 50mm x 3mm                                                                                      £12.82                                   www.aluminiumwarehouse.co.uk

·         Centre Mounts – 165mm x 165mm x 5mm                                                           £10.37                   www.aluminiumwarehouse.co.uk

Lifting tackle

·          Bow shackles – STEEL – 2 at a working load 2.3 tonnes                                   £8.38                     www.machinemart.co.uk

·         Lifting hooks – STEEL – 4.5 inches – 2 tonne working load                              £35.89                   www.ecrater.co.uk

·         D rings – STEEL – 2 inches – 1.1 tonne working load                                          £1.95                                     www.simplyscuba.co.uk

Pins & Clips

·         Steel pins (top beam) – 4 at £0.30                                                                             £1.20                                     www1.mcsdirect.com

·         Steel pins (assembly pins) – 12 at £0.33                                                                  £3.96                                     www1.mcsdirect.com

·         R clips - 40mm -16 at £0.10                                                                                           £1.60                                     www1.mcsdirect.com

Lifting Harnesses

·         Lifting slings – 4m with 2m lift – 2 tonne capability – 4 at £5.10                     £20.40   www.scaffolding-direct.co.uk

·         Lifting straps – 2m – 2 tonne capability – 3 at                                                       £3.95   

www.megatradestore.com

·         Ratchet strap -  38mm x 6m – 2 at £9.13                                                                 £18.26                                   www.power-tools-pro

Total Cost Per Kit:

A full list of parts and components can be found in a table at Annex of the Appendices. The full price for one unit in parts works out to be £874.33 and the remaining overheads include:

-          Part Fabrication -      £240 / Unit

-          Labour Costs -           £50 / Unit

-          Packaging -                 £5 / Unit

The overheads include provision of materials for each process and completion of each process also bringing the total cost per kit to £1169.33 per Unit.

To ensure our Company remains profitable we will put a 40% profit margin onto the RRP meaning that the modular crane kit can be offered at a per unit price of £1637.06.

Sub-Contracts:

The majority of the parts for our crane come from material suppliers in an inoperable condition and require fabrication. For this reason we will be using sub-contracted companies to carry out the following roles:

-          Fabrication (welding of components into parts) – local company.

-          Material Suppliers (e.g. www.aluminiumwarehouse.co.uk)

-          Kit Assembly / Packaging – local company

By using sub-contracts we are able to provide discounted rates to the unit price for high demand orders based on requirements.

Further Considerations:

The Company are able to compliment the current crane kits if successful at tender by offering a range of additional lifting tackle, spares and servicing packages. The basic crane kit meets all of the design brief points to good effect and can be compared to similar products already on sale within various markets:

Competitive Company Comparison:

“Lifting Safety” is a nationally recognised company who retail a full range of small, medium and large Aluminium gantry cranes, capable of lifting between 0.5 and 5 tonnes. The target users include vehicle mechanic companies, building sites and other low level industrial type uses. It could be easily adapted to go to tender for this design brief.

In comparison to the Taurus Integrated Technologies crane kit it is less functional due to its limited leg adjustability and does not include any lifting tackle or harnessing to move loads. It is also less durable due to its grade of aluminium and is vulnerable to salt corrosion; adversely affecting its lifespan within the role we can cater for.

The most significant comparison is the cost. “Lifting Safety” produce a small gantry crane of similar dimensions which has a RRP of £2100 per unit. This is a difference of £462.94 per unit meaning that if a 3^rd World Country were to require 10 units, we could offer a saving of £4629.40 without considering the reduced unit price we could offer for a bulk demand.

Fig. 1 – A table showing the range of gantry cranes available from ‘Lifting Safety’ and the price per unit.

Conclusion:

By finding suppliers of standard parts and materials and using sub-contracts with local companies, Taurus Integrated Technologies have produced a highly functional, competitively priced Emergency Crane kit which will be of high demand to any potential users.

Company Reference:

http://www.liftingsafety.co.uk/product/aluminium-gantry-crane-3085.html#pricing

Lifting Gear and Weak Link

Lifting Sling/Strap Material

The lifting Slings we intend to use are made out of a material called high tenacity polyester yarn which is renowned for its hardwearing properties. Widely used through out industry and construction due to their low weight, flexibility and ease of use. These lifting slings are also relatively cheap with an example of lifting capabilities and prices from lift safe solutions below;

For our Gantry crane, it is recommended that we supply our product with straps capable of lifting 2 tonne to ensure durability through use and be at least 6m in total length to ensure it can deal with awkward loads.

Source: www.liftsafesolutions.co.uk

Bow Shackle Material

When deciding which material would be best suited to use for our bow shackles, it came down to two options, high tensile or stainless steel. High Tensile steel would offer us extreme durability and strength at a relatively low cost; however from our design specification, it is clear that the crane will be used in disaster areas, it is therefore accepted that the crane must be durable in all weather conditions. This therefore lead us to turn to using stainless steel Bow Shackles, which still offer great strength yet also offer good corrosive resistance. An example of the load capacity and price for an ideal Bow shackle can be seen below.

Source: www.s3i.co.uk

D ring limits to fail before 1.2 tonnes to prevent damage to crane.

With our D-rings also being manufactured from stainless steel it is accepted that it is more likely that the crane will fail before any of the lifting gear. As a result of this it has been seen as a good idea to implement a safety device within the design to ensure the protection of the main crane assembly, this will ensure longer product life and serviceability, key for our design success. To this end, we have proposed that all our D-rings, which connect the load to the pulley system be designed to fail when it is loaded with more than 1.2 tonnes, a safe loading limit with enough leeway either side of 1 tonne to ensure safe operation of the crane. 

Stress Analysis of Foot Poles

Stress analysis was carried out for the foot poles, modelling the quadpod centre as a built in joint and the tube as a beam. The load was considered as acting upwards from the floor, as it would in a reaction force. The weight of the part itself was considered negligible.

Deflection was calculated first:

Which comes out at 0.5mm and will not affect the performance of the part.

Then max stress:

Which shows it will not fail.

Stress analysis of Top Beam

The top beam was analysed to find the maximum deflection and maximum stress, as shown below.

I = Second Moment of Area and y = distance between load and COM of beam.

Yield Stress is 503 MPa, so the beam will not permanently deform under load

In this case y represents deflection.

This small amount of deflection will not affect the operation of the crane.

Bearings for use in Gantry Crane

The bearings that we have opted to use are known as barrel roller bearings. We have opted for this design as they are known for their ability to cope with high axial loads and have the ability to cope with misalignments which may happen when loading the crane on planes which are not perfectly level, which is a realistic situation as the crane will be used in undulating terrain.

The requirements for our bearings are as follows, take a min load of 262.5kg each, have an inside diameter of 20mm, outside diameter of 47mm and a width of 14mm.

As a result the Gantry system will require 8 of these bearings for the running gear on the top beam of the gantry. 

The Bearing shown below is manufactured by a company called Shaeffler, a German company specialising in bearings for use in industry.

The bearings that we have opted to use are known as barrel roller bearings. We have opted for this design as they are known for their ability to cope with high axial loads and have the ability to cope with misalignments which may happen when loading the crane on planes which are not perfectly level, which is a realistic situation as the crane will be used in undulating terrain.

The requirements for our bearings are as follows, take a min load of 262.5kg each, have an inside diameter of 20mm, outside diameter of 47mm and a width of 14mm.

As a result the Gantry system will require 8 of these bearings for the running gear on the top beam of the gantry. 

The Bearing shown below is manufactured by a company called Shaeffler, a German company specialising in bearings for use in industry. 

A priced example, £20.13 per unit.

Final Design

The design has now been finalized for the crane, and drawn in CAD. Dimensions were adjusted in response to CAD optimization and stress analysis calculations, as well as real life considerations such as making material dimensions that are easy to source.

It is shown below:

Final Assembly

Lifting Block Carrier

Top Beam

End Upright

Quadpod

Feet

Beam to column joint in detail. (Will be welded to box section upright)

Assembly Pins

Top Beam Pins

Winching System Selection

It was decided that and electrical winching system would be more unreliable than a pure mechanical system. Another disadvantage is the fact that it needs power to operate; this would mean that a power source will need to be present. This could only be done in a couple of ways either connecting it to the Landover’s power source or having a generator. Therefore, it was decided that the western differential pulley system would be the best system to use for this task because of its simplicity and ability to get large mechanical advantages easily.

Optimizing Crane Dimensions

The crane was initially modelled in Solidworks with estimated dimensions to create the basic design of the crane. Convenient numbers were used to make modelling quicker.
The individual parts were then analysed using SimulationXpress Analysis Wizard in Solidworks, by applying the maximum loads which the individual components will have to withstand, and fixtures where the parts will be joined together. The material which was applied was 7075-T6 aluminium from the pre loaded materials file. The optimize tool was then used by selecting dimensions which may be changed (within reasonable applied limits) and dimensions which must stay the same for functional reasons (eg length of top beam) to reduce the mass of the components. Maximum deflection limits were also inputted in order to ensure that no functionality was lost in the alteration of these dimensions. The wizard then gave optimal suggested dimensions and produced diagrams to show where maximum stress and deflection occurred. It also gave masses for each part.
Manual calculations will now be used in order to do stress analysis of the structure, and check for failure methods which may not have been accounted for in the simulations such as buckling.

The stress diagrams and deflection diagrams are shown below:

Deflection Diagram of Top Beam

Stress Diagram of Top Beam

Displacement diagram of Feet Poles

Stress diagram of Feet Poles

Displacement diagram of End Joint

Stress diagram of End Joint

Aluminium Type Decision

From research into materials, 7075 aluminium has been chosen as the type of aluminium which will be used for the crane. This is due to its high strength and corrosion resistance which means it does not require any form of coating. It is also one of the easiest aluminium alloys to weld, most commonly and effectively welded using resistance welding, which is a very quick form of welding. It has a greater springback capability than most forms of aluminium which is also useful in this application where it may suffer a large amount of abuse in the situations it will be required.

http://www.suppliersonline.com/propertypages/7075.asp

Bearing Decision

 

From the research which has been presented roller bearings have been chosen for use in the crane because of the load that they will experience in this application. This is because they will experience a  high radial load with a negligible thrust load, which is what this type of bearing is designed to cope with. They have also been chosen as they are available as a sealed cartridge unit which requires no maintenance in it's lifecycle. This makes them preferable to plain bearings because although they have a greater resistance to axial load, they require good lubrication to work and maintenance to keep them in working order.