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COMPARATIVE STUDY AND EVALUATION OF SPARE PARTS FOR SEPARATORS IN NAVAL APPLICATION

New Materials Technologies Instituteein Technologietransferzentrum der

TTI GmbH an der Universität Stuttgart

Short Summary on Materials Testing and Analysis

Steel Components: Worm with Gearing (part no. 520320-08)

Parts that were analyzed Steel parts • Worm with gearing Heat treatable steel C45 • Bowl Spindle Heat treatable steel C45

Polymer parts • Seal Rings Polyamide PA66

• Rectangular Rings Nitrile rubber compound NRC • O-Rings Nitrile rubber compound NRC

- bearing seats- gearing

- bearing seats- cone position

- diameter- height / width (upper- and lower face)

- diameter- width

- diameter- width

- hardness / elastic indentation- modulus

- hardness / elastic indentation- modulus

- hardness

- hardness- tensile strength

- hardness- tensile strength

Worms (C45)Parts no. 520320-08

Bowl Spindles (C45)Parts no. 67641

Seal Rings (PA66)Parts no. 541691-02 521875-01 71440-00

Rectangular Rings (NRC)Parts no. 545800-01/02/003 543446-03 521863-01 67575-00

0-Rings (NRC)Parts no. 67587

2

2

6

12

2

- chemical analysis- metallography

- chemical analysis- metallography

- thermal analysis- microscopy- optical comparison

- analysis extractable elements- spectroscopy- thermal analysis- optical comparison

- optical comparison

Measurements performed during the study

components no. of analyzed properties / measurements samples geometrical mechanical other

Gear measuring center:rotatable mounting device and measuring head

Position of componentcoordinate systems forworm and bowl spindle

and planning of analysisof the dimensional and

positional tolerances

Geometrical analysis of: quality of the gearing Gear measuring center dimensional and positional tolerances of the bearing seats 3D-coordinate measurement machine

Design sketch of Chiefmar worm component:

Comparative Study and Evaluation of Spare Parts for Separators in Naval ApplicationProject Report for Chiefmar s.r.l., Genova, Italy






a grain size of Chiefmar material is slightly larger, pearlite is �ner for Alfa Laval material mechanical properties will be poorer in small extent for Chiefmar components this effect is mainly for the near-surface region

large difference in pearlite structure for material in the components' core suggests very slow cooling of the Chiefmar material will be improved by heat treatment of component after machining

Light optical micrographs of gearing teeth, Chiefmar and Alfa Laval wormsLeft: overview of the microstructureRight: material in the center of the gear teeth with higher magnification

Chiefmar gear tooth, Core materialChiefmar gear tooth, Overview

Alfa Laval gear tooth, Core materialAlfa Laval gear tooth, Overview

Measurement report of the Chiefmar Measurement report of the Alfa Laval gearing

Quality of the Worm Gearing (Pro�le and Trace Analysis)

Metallography of the Worm Gearing

α

F = 0

α

h

F




Microstructural Analysis of the Worm Bearing Seats (Metallography)

Hardness Analysis by Vickers Indentation on Worm Components

analyzed positions: gearing and bearing seatslocation of the metallographic preparations

grain sizes are comparable

differences are low between surface and core material

Chiefmar, bearing seat A, core Alfa Laval, bearing seat A, core

Chiefmar worm gearing tooth tip Alfa Laval worm gearing tooth tip

Alfa Laval, bearing seat A, surface

Chiefmar, bearing seat A, surface

manufacturer bearing seat A bearing seat B

Chiefmar 205 HV 0.102 230 HV 0.102

Alfa Laval 292 HV 0.102 269 HV 0.102

Table: Vickers hardness, average values over the measuring depth for gearing teeth

bearing seats: overall comparable hardness values, but higher surface hardness for Alfa Laval material can be improved by surface heat treatment gearing: same hardness range; gradient for Chiefmar material from tooth tip to base.

Table: Surface Vickers hardness of bearing seats

Vickers hardness/depth profiles for bearing seats

Light optical microscopies of the indentations for Vickershardness/depth profile analysis on worm gearing tooth tips

Principle of the indentation test method forhardness measurement (Martens hardness):

Location of metallographic preparations:




Steel Components: Bowl Spindle (part no. 67641)

Main Results of the Study: Steel Components

Location of metallographic preparations on spindle components

Further analysis: material analysis microscopy hardness measurement (Vickers hardness and elastic indentation modulus) chemical analysis (EBMA* method)

Geometrical analysis of: dimensional and positional tolerances of the bearing seats and of the cone SD-coordinate measurement machineResults: more accuracy for Chiefmar spindle except for the cone position easy to �x problem

analyzed positions: cone and bearing seatslocation of the metallographic preparations

* EBMA: Electron Beam Microprobe Analysis

C45 Worm Components:

Dimensional and Positional Tolerances

C45 Spindle Components:


Materials Properties


• Gearing: Better tolerances and quality (tooth profiles and flank shapes as well as gear pitches) for Chiefmar than Alfa Laval, but finishing of the edges could be improved

• Bearing seats: positional tolerances were good for all parts• Bearing seats: dimensional tolerances have to be improved for Chiefmar parts by better

machining accuracy

• Higher accuracy (in general) for the Chiefmar component• The cone of the spindle has to be improved by better accuracy and manufacturing

metrology during machining

• Material: similar material for Chiefmar worm and spindle component (C45), while Alfa Laval material could be lower alloyed (e.g. C40)

• No heat treatment of the materials for both manufacturers and no differences in microstructures

• Hardness of the bearing seats is slightly higher for Alfa Laval components• Heat treatment of bearing seats could improve the mechanical properties in a large extent

• Material: heat treatable steel for Chiefmar and Alfa Laval with no remarkable differences (Alfa Laval material could be C60, but this is not sure; Chiefmar material is C45)

• Heat treatment: was not done for both manufacturers; however, a heat treatment process would improve the mechanical properties of the gearing and the bearing seats

• Mechanical properties: similar for the two manufacturers; could easily be improved at critical regions (bearing seats) by heat treatment like annealing or surface hardening




Material Analysis for Seal Rings

Polymer Components: Rectangular Rings and O-Rings

Thermal analysis with the DSC method (differential scanning calorimetry): material was identi�ed as polyamide 66 for Chiefmar and Alfa Laval (same melting temperatures) small differences in melting enthalpy and crystallization temperature there are differences in the composition or structure (cross linking) of the �nal polymers thermal durability slightly higher for Chiefmar material

Geometrical analysis of:

diameter of the rings patented optical measuring device

cross section height and width measurement with laser scan micrometer

PA66 seal rings, results of the DSC analysis during heating

8,0

R 2,

8,0

Ø 419,00

Further analyses:

mechanical properties hardness analysis (Shore A) and tensile testing

standardized material analysis thermogravimetric analysis (TGA) extraction analysis Fourier transform infrared (FT-IR) spectroscopy

Schematic setup ofShore A hardness testson NRC rectangular rings:

Design sketch of Chiefmar rectangular ring:

Parts no. 545800-01/02/003, 543446-03, 521863-01, 67575-00 (rectangular rings) and 67587 (o-rings)

Results geometry: good analogy between Chiefmar and Alfa Laval rectangular rings and o-rings hardness: hardness differences are small (negligible) no hardness in�uence on operation behavior




Mechanical Properties of Rectangular Rings and O-Rings

Chemical Composition of NRC Rings

Load-displacement diagramof tensile tests on NRCrectangular rings and o-rings

load-displacement curve!

spec. no. load maximum load at 100 mm load at 200 mm load at 300 mm load at 400 mm remarks (N) (N) (N) (N) (N) 001-O-CH 153 50 80 108 132 max. elongation 002-O-AL 160 47 72 97 127 max. elongation

Table: Results of tensile tests on NRC o-rings according to DIN 53504

Tensile test results

statistical accuracy is not given due to low number of test specimens

rectangular rings: trend to higher strength for Alfa Laval rings

o-rings: difference in tensile strength is negligible

Material analysis of nitrile rubber compound (NRC) for rectangular rings:

thermogravimetry discovers larger fraction of elastomers for Alfa Laval material

extraction and subsequent FT-IR spectroscopy yield the chemicals used for plasti�cation (plastisizers) differences in the chemical composition of the plastisizers

materials are quite similar, but with some differences in chemical composition and mass fractions of polymers, plastisizers and �llers

Superposition of FT-IR-spectroscopies of thepyrolyzates of Chiefmar(blue) and Alfa Laval (red)rectangular rings

Consistent ingredients of the pyrolyzates of extractabIe elements: butadiene and acrylonitrile

Remark:

Only one Chiefmarring and one from AlfaLaval were analyzeddue to high costs ofthe analysis!




Main Results of the Study: Polymer Components

Summary and Conclusions

PA66 Seal Rings:


NRC Rectangular Rings and O-Rings:


Manufacturing Process

• Quality of dimensional tolerances is the same for the two manufacturers (could be improved)• Quality of the cross section shape could be improved for both manufacturers; this could

be achieved by more remaining (cooling) time of the component in the die after injection moulding

• Die is different with respect to number of injection gates; this means that the manufacturing process should be optimized in terms of polymer mass temperature, die temperature and mould release agent that are used

• Hardness: higher for Chiefmar components, and thereby, the elastic modulus is higher as well• Thermal behaviour (melting and solidification): shows that PA66 was used by both

manufacturers; thermal durability is higher for the Chiefmar material (indicates that the molecular arrangement of the polymer is different due to different manufacturing parameters)


Material Composition(analysis of 2 rings only!)

Mechanical Properties

• Geometry and dimensions of the various rings are comparable for Chiefmar and Alfa Laval• Differences in the dimensions of the rectangular ring cross sections in the region of

0.2-0.3 mm• Hardness: Measurement by Shore A showed same hardness for both manufacturers• Tensile strength: difficult measurements due to limited number of test components; almost

no difference in strength (with a small trend to higher values for Alfa Laval NRC rings)• Thermal decomposition analysis: mass fractions of volatile constituents, polymeric

fractions, carbon and ash filler material similar with slightly larger fractions of elastomers for Alfa Laval (5 wt.% more) and filler material for Chiefmar (2 wt.% more)

• Elemental analysis (spectroscopy) of extractable elements: rather similar materials of the two manufacturers with differences in chemical composition of the plasticizers (diluents)

• Differences between Chiefmar and Alfa Laval components are small, both for polymer and steel components• Chiefmar steel components have similar material like Alfa Laval components; material properties only differ

slightly, but Chiefmar could improve their components significantly by additional heat treatment at critical positions (like bearing seats)

• The accuracy of the steel components is in general comparable; however, a better attention on manufacturing metrology (e.g., length measurements) will improve quality and lead to better overall performance

• Dimensional and mechanical properties of the polymer parts are very similar between the two manufacturers (higher hardness of the Chiefmar PA66, higher strength of the Alfa Laval NRC)

• For the seal rings, optimization of the manufacturing process would increase component properties and accuracy (e.g., better cooling after manufacturing)

• For the NRC material (rectangular rings and O-rings), there are differences in chemical composition; larger fractions of elastomers could lead to better tensile strength of the Alfa Laval rings; however, the true influence of different polymers and plastisizers (or diluents) in the NRC materials cannot be appointed for sure, because the composition of rubber compounds is complex

• All measurements in this study were made on new polymer and steel components from Chiefmar and Alfa Laval. Therefore, statistical evidence of the results is not possible. If customers would return damaged parts, failure analysis could lead to better understanding of specific application-oriented problems and improvement of the component design and manufacturing.

Chiefmar s.r.l. Via G. Adamoli, 261 - 16138 Genova - Italy - ph. +39 010 8360219 - fax +39 010 8360912

[email protected]

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