Idm Report Group 5

8/3/2019 Idm Report Group 5

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SPIRAL STAIRCASE

A report for Space Solutions

By IDM GROUP 5



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1. Introduction

As a consulting company in engineering of international class we are very pleased to present you our

solution for a design and a manufacturing process of a spiral staircase.

The designing process began with an extensive research on the customer’s requirements to specify

the attributes of a spiral staircase. By using Quality Functional Deployment matrices for the design as

well as the installation process the present design was developed. Insofar as there is a potential need

of spiral staircases in the private sector our design is as customizable as possible to satisfy each

individual demand. The modular design ensures that all parts can easily be transported even into

small or contorted rooms. A clear structured user guide and the simple assembly of the staircase

result in an easy and without any specific knowledge to assemble design. Since most of the parts are

supposed to be manufactured in-house our manufacturing plan tries to ensure this. However, it is

considering that a start up firm does possibly not have the financial support to equip a factory on thehighest technological level. Additionally it will presumably not be able to run a mass production from

the very beginning of their enterprise.

Please find both Quality Functional Deployment matrices as well as the complete part and assembly

drawings in the appendix.

Yours sincerely

IDM GROUP 5



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2. Table of contents

Page:

1. Introduction 2

2. Table of contents 3

3. Design 4 - 5

4. Manufacturing considerations

4.1 Bill of materials

4.2 Machines and tools required

4.3 Manufacturing Process

6 - 8

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7 - 8

5. Appendix

5.1 Design Quality Functional Deployment matrices 1-4

5.2 Installation Quality Functional Deployment matrices 1-2

5.3 Assembly drawings

5.4 Part drawings

5.5 User guide

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Fig. 1 – “Column and flange“

Fig. 2 – “Collar”

Fig. 3 – “Handrail Rods”

3. Design Choice

Insofar as all customer requirements were supposed to be satisfied the current design was chosen.

The requirements for a “Private Stair” (according to BS 5395) were subdivided in the six categoriesSafety, Quality, Competitiveness, Ergonomics, Manufacturing and Maintenance as well as

Sustainability. These are including several attributes like fire protection, long design life, a modular

design and a variable height (cf. QFD Design). Moreover most of the requirements were quantified to

comply with the British Standard (BS). Afterwards functions of the staircase, whose compliance was

also quantified, were considered to ensure that the final design satisfies all requirements. Some

functions are for example to hold a vertical load or to prevent the user from falling down (cf. QFD

Design).

The chosen modular staircase-design fulfils all customer

requirements and is easy as well as without any specific knowledge toassemble. It consists of several different parts. The column (to be

seen in Fig.1), which is connected to the ground by a flange (Fig.1),

stabilises the entire staircase, holds parts of the load and can easily

be extended to span at least two floors. The flange has a rectangular

area, because with this it can be mounted to a concrete floor as well

as to a timber joist floor construction.

The “Collar” (to be seen in Fig.2) is the most important part to

hold a vertical load. It is also important to locate and fasten the

stairs, which are connected to the collar with bolts and nuts.

However, one has to distinguish between a normal stair and a landing stair. The landing stair is

broader and has therefore a wider angle compared to the normal stair. It is either a top stair or a

landing stair in the middle of the staircase. The top stair is a stair at storey levels with an angle of at

least 60° to ensure that the user can easily leave the staircase. The landing stair in the middle is an

intermediate or rest landing with an angle of at least 45°. It should according to the British Standard

BS 5395 generally be inserted after 16 normal steps. The present design provides every kind of

landing, just depending on the customer’s requirements. Customized and specifically ordered

landings can if necessary be manufactured.

To prevent the user from falling down, the staircase has an outer handrail. It consists of a hose made

of an elastomer. The elastomer makes the handrail safe

to use, because it is easy to grab and does not slip.

Additionally rods are connecting the handrail to the

stairs. The rods are also ensuring that no small children

could possibly fall through the stairs. One rod per stair

secures one stair to another, as it is poked through the

upper stair and fixed to the stair below (seen in Fig.3).



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Fig. 5 – “Spacer”

Fig. 6 – “Top Nut”

Fig. 4 – “Collar

Connection Element”

Thus all steps are located and fastened, because the landing stair on the top is fixed to the upper

level and the step at the bottom is fixed to ground. On the final level an extra handrail is needed to

make sure that nobody could possibly fall from this level. It also consists of the same parts which

were used for the normal handrail.

To damp vibration and to adjust the collar to the column in an

appropriate way the “Collar Connection Element” (black element in Fig.4)

was designed. It consists of an elastomer and fits very accurately to the

different surfaces of the collar and the column.

To adjust the height of the

staircase two different

“Spacers” were designed

(metal ring in Fig. 5), one witha height of 10mm and another

one with the height of 20mm. Insofar as the rise of the

stair could, according to the BS and depending on the

customized problem, vary between 170mm and 220mm the spacers are needed to adjust the height

of the staircase. With these two sizes of spacers a gap of less than 10mm at the final floor will be

guaranteed.

The “Top Nut” (to be seen in Fig. 6) is screwed on top of the column to secure

that the collars are fixed and fastened. Additionally a rod for the handrail of thefinal level is screwed into the top nut.

Further to this the customer can chose different top stair covers. As the normal

stair is made of steel, it is probably not very convenient to have it in your

private house without any stair cover. A carpeted stair is as well provided as a

laminated, which could look like a wooden stair for example. Also a vinyl

covered stair with a lot of different patterns is available. All covers fulfil the BS fire protection

requirements and fit with the provided different colour options for all other parts of the staircase.

Please find the entire Quality Functional Deployment matrices for the staircase-design in the

appendix.



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4. Manufacturing considerations

4.1 Bill of materials

Assembly Sub-assembly Part Quantity Material

Part No Description Level 1 Level 2 Level 3

IDM_2011_001 SPIRAL STAIRCASE IDM_2011_001 1 N/A

IDM_2011_004 STAIR ASSEMBLY IDM_2011_004 VARIES N/A

IDM_2011_045 STAIR IDM_2011_045 1 EN3B MILD STEEL

IDM_2011_015 COLLAR IDM_2011_015 1 EN3B MILD STEEL

IDM_2011_042 MIDDLE ROD IDM_2011_042 1 EN3B MILD STEEL

IDM_2011_040 LOCATING ROD IDM_2011_040 1 EN3B MILD STEEL

IDM_2011_041 LOWER ROD IDM_2011_041 1 EN3B MILD STEEL

IDM_2011_023 COLLAR CONNECTION IDM_2011_023 1 ELASTOMER

IDM_2011_003 FIRST STAIR ASSEMBLY IDM_2011_003 1 N/A

IDM_2011_045 STAIR IDM_2011_045 1 EN3B MILD STEEL

IDM_2011_014 FIRST COLLAR IDM_2011_014 1 EN3B MILD STEEL

IDM_2011_024 FIRST COLLAR CONNECTION IDM_2011_024 1 ELASTOMER


IDM_2011_041 LOWER ROD IDM_2011_041 1 EN3B MILD STEEL

IDM_2011_042 MIDDLE ROD IDM_2011_042 1 EN3B MILD STEEL

IDM_2011_040 LOCATING ROD IDM_2011_040 2 EN3B MILD STEEL

IDM_2011_005 FINAL STAIR ASSEMBLY IDM_2011_005 1 N/A

IDM_2011_046 FINAL STAIR IDM_2011_046 1 EN3B MILD STEEL

IDM_2011_015 COLLAR IDM_2011_015 1 EN3B MILD STEEL


IDM_2011_044 LANDING STAIR ROD IDM_2011_044 7 EN3B MILD STEEL

IDM_2011_050 TOP BRACKET IDM_2011_050 2 EN3B MILD STEEL

IDM_2011_006 LANDING HANDRAIL ASSEMBLY IDM_2011_006 1 N/A

IDM_2011_062 LANDING HANDRAIL IDM_2011_062 1 ELASTOMER

IDM_2011_061 HANDRAIL INSERT IDM_2011_061 8 EN3B MILD STEEL

IDM_2011_036 FLANGE ASSEMBLY IDM_2011_036 1 N/A

IDM_2011_035 THREADED BOLT IDM_2011_035 1 EN3B MILD STEELIDM_2011_034 PLATE IDM_2011_034 1 EN3B MILD STEEL

IDM_2011_002 HANDRAIL ASSEMBLY IDM_2011_002 1 N/A

IDM_2011_060 HANDRAIL IDM_2011_060 1 ELASTOMER

IDM_2011_061 HANDRAIL INSERT IDM_2011_061 VARIES EN3B MILD STEEL

IDM_2011_030 COLUMN IDM_2011_030 1 EN3B MILD STEEL

IDM_2011_031 TAILORED COLUMN IDM_2011_031 1 EN3B MILD STEEL

IDM_2011_016 10mm SPACER IDM_2011_016 OPTIONAL EN3B MILD STEEL

IDM_2011_017 20mm SPACER IDM_2011_017 OPTIONAL EN3B MILD STEEL

IDM_2011_033 TOP NUT IDM_2011_033 1 EN3B MILD STEEL

IDM_2011_043 TOP NUT ROD IDM_2011_043 1 EN3B MILD STEEL

M10 COUNTERSUNK BOLT M10 VARIES N/A

M10 NUT M10 2

M16 BOLT M16 4 N/A

Fig. 7 - “Bill of Materials”



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4.2 Machines and tools required

CNC Milling machine – working envelope circa 1000x500x500mm

Pillar Drill –to avoid the CNC having a backlog of work to do

Metal cutting band saw – to cut maximum 20mm thickness22mm circular cutter /corer

M10 tap

M16 die

M20 tap

M70 x 6 die

M70 x 6 tap

MIG welder

Operations for manufacturing the collar connection elements and the handrails are to be outsourced

as the start-up cost of purchasing injection moulding machines etc is too high.

4.3 Manufacturing Process

Flange assembly, columns and spacers

The flange plate will be cut down using the band saw from a mild steel plate to the correct

dimensions and the holes for the M10 bolts drilled on the pillar drill. The threaded bolt will be cut

down using the band saw from a standard length of mild steel pipe. The thread will be tapped

manually using the M70 x 6 tap. The plate and the threaded bolt will then be welded together.

The columns’ will be cut down to size (1500mm for the standard column and the required height for

the customer for the tailored column) using the band saw. A CNC or manual lathe with a large

enough working envelope to fit the column in would be prohibitively expensive for the number of

operations that it would perform. Hence the threads have been chosen to be cut manually despite

the expensive of the specialist tap and die.

The spacers are made to order by cutting a standard length mild steel tube down to either the 10mm

or the 20mm size as required by the customer.

The top bracket will be bought in as one component then the holes added manually using the pillar

drill. Manufacturing it in house would require purchasing a sheet metal folding machine for just the

one operation so is too expensive.

Stairs, collars and rods

The collar is made up of three parts that are welded together. The circular element is cut from a

standard length pipe on the band saw and then undergoes an operation on the CNC mill to machine

a slot onto the outer profile. The plate that connects to the stair is machined in the CNC mill to shape

the circular profile. To free up the CNC machine the holes are drilled and counter bored manually onthe pillar drill. The supporting triangular plate is cut on the band saw and then all three components

are welded together to make up the collar.



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The stairs are machined from mild steel in the CNC mill to get the circular outer profile the holes

drilled on the pillar drill and then tapped using the M10 tap. For the landing stair to be solely

manufactured in the CNC mill the mil would have to have a very large working envelope making it

too expensive. To counter this problem the landing stair is manufactured in two halves which are

then welded together allowing a smaller mill to be used.

The collar connection element is injection moulded out of an elastomer, this process would be

outsourced due to the cost of an injection moulding machine being too large for the amount

operations it would perform.

The rods are cut from a standard length rod using the band saw and the external thread is then cut

using the M10 die.

Handrail

Both of the handrails comprise of two distinct components. The handrail its self and a tapped insert

to facilitate its attachment to the rods. The tapped insert is made out of mild steel and tapped

manually using an M20 tap. The handrail will be manufactured by extruding the outer profile to give

the length tailored to the customer’s stair requirements. This is another process that would be

outsourced due to the excessive cost for machines for just a single operation. The elastomer handrail

would then have circular inclusions manually cut and the insert bonded in with an adhesive.

Idm Report Group 5

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