Tuesday, 5 February 2013

Hydraulic System Design



Hydraulic System Design

 
Fig-1

Hydraulic systems can generally be broken down into various types of systems based upon the primary application. For example, on an earthmoving machine, the Primary objective of the hydraulic system is to transmit power efficiently to the various circuits of the machine.

On the other hand, a machine tool application is primarily concerned with speed, accuracy, and stability of the hydraulic systems. Once the design goals are established for a given hydraulic system, the actual design Process can be initiated.

The generalized hydraulic system design and analysis process is illustrated in Fig. 1. From the design goals, the design concept to be integrated into the hydraulic system must be established and a system schematic must be developed along with the operational specifications for the system.

Once these tasks are completed the designer will get into component sizing and selection process. Generally when the sizing and selection phase was completed, the components would be purchased and a proto type system constructed.

The system performance was not simulated and the success of a particular system was mainly a result of the experience of the designer past experience. The actual performance characteristics were evaluated through laboratory and field tests using the system prototype.

Optimization was a function of a process which was normally called "cut and try". This optimization mostly applicable for existing product thru Value engineering project.

Mohammad Arif, ME, MIET(UK), CEng




Wednesday, 23 January 2013

New Product Development

New product Development

Given the rapid changes in technology and competition, companies must develop a steady stream of new products and services. A firm can obtain new products in two ways.
One is through acquisition—by buying a whole company, a patent, or a license to produce someone else's product. This is more like inorganic growth and easy to do with cash. But organic growth is the one which gives your customer same product (same family) irrespective of manufacturing location. 
The other is through new-product development in the company's own research and development department. By new products we mean original products, product improvements, product modifications, and new brands that the firm develops through its own research and development efforts. In this chapter, we concentrate on new-product development.
New products continue to fail at a disturbing rate. Why do so many new products fail? There are several reasons.
·         Although an idea may be good, the market size may have been overestimated.
·         The actual product was not designed as well as it should have been.
·         May be it was incorrectly positioned in the market,
·         Priced too high, or advertised poorly.
·         A high-level executive might push a favorite idea despite poor marketing research findings.

Sometimes the costs of product development are higher than expected, and sometimes competitors fight back harder than expected because so many new products fail, companies are anxious to learn how to improve their odds of new-product success.

One way is to identify successful new products and find out what they have in common. Another is to study new-product failures to see what lessons can be learned. Various studies suggest that new-product success depends on developing a unique superior product, one with higher quality, new features, and higher value in use. Another key success factor is a well-defined product concept prior to development, in which the company carefully defines and assesses the target market, the product requirements, and the benefits before proceeding. Other success factors have also been suggested senior management commitment, relentless innovation, and a smoothly functioning new-product development process. In all, to create successful new products, a company must understand its consumers, markets, and competitors and develop products that deliver superior value to customers.

So companies face a problem, they must develop new products, but the odds weigh heavily against success. The solution lies in strong new-product planning and in setting up a systematic new-product development process for finding and growing new products.

1) Idea Generation: New-product development starts with idea generation—the systematic search for new-product ideas. A company typically has to generate many ideas in order to find a few good ones. Major sources of new-product ideas include internal sources, customers, competitors, distributors and suppliers, and others. Using internal sources, the company can find new ideas through formal research and development. It can pick the brains of its executives, engineers, manufacturing, and sales people. Some companies have developed successful "intrapreneurial" programs that encourage employees to think up and develop new-product ideas.
Good new-product ideas also come from watching and listening to customers. Competitors are another good source of new-product ideas.
The search for new-product ideas should be systematic rather than haphazard. Otherwise, few new ideas will surface and many good ideas will sputter in and die. Top management can avoid these problems by installing an idea management system that directs the flow of new ideas to a central point where they can be collected, reviewed, and evaluated. In setting up such a system, the company can do any or all of the following:
  • Appoint a respected senior person to be the company's idea manager.
  • Create a multidisciplinary idea management committee consisting of people from R&D, engineering, purchasing, operations, finance, and sales and marketing to meet regularly and evaluate proposed new-product and service ideas.
  • Set up a toll-free number for anyone who wants to send a new idea to the idea manager.
  • Encourage all company stakeholders—employees, suppliers, distributors, dealers— to send their ideas to the idea manager.
  • Set up formal recognition programs to reward those who contribute the best new ideas.
The idea manager approach yields two favorable outcomes. First, it helps create an innovation-oriented company culture. It shows that top management supports, encourages, and rewards innovation. Second, it will yield a larger number of ideas among which will be found some especially good ones. As the system matures, ideas will flow more freely. No longer will good ideas wither for the lack of a sounding board or a senior product advocate.
2) Idea Screening: The purpose of idea generation is to create a large number of ideas. The purpose of the succeeding stages is to reduce that number. The first idea-reducing stage is idea screening, which helps spot good ideas and drop poor ones as soon as possible.
3) Concept Development and Testing: An attractive idea must be developed into a product concept. It is important to distinguish between a product idea, a product concept, and a product image. A product idea is an idea for a possible product that the company can see itself offering to the market. A product concept is a detailed version of the idea stated in meaningful consumer terms. A product image is the way customers perceive an actual or potential product.
Marketing strategy development: The next step is marketing strategy development, designing an initial marketing strategy for introducing this car to the market.
The marketing strategy statement consists of three parts.
The first part describes the target market; the planned product positioning; and the sales, market share, and profit goals for the first few years.
The second part of the marketing strategy statement outlines the product's planned price, distribution, and marketing budget for the first year:
The third part of the marketing strategy statement describes the planned long-run sales, profit goals, and marketing mix strategy:
4) Business Analysis: Once management has decided on its product concept and marketing strategy, it can evaluate the business attractiveness of the proposal. Business analysis involves a review of the sales, costs, and profit projections for a new product to find out whether they satisfy the company's objectives. If they do, the product can move to the product development stage.
To estimate sales, the company might look at the sales history of similar products and conduct surveys of market opinion. It can then estimate minimum and maximum sales to assess the range of risk. After preparing the sales forecast, management can estimate the expected costs and profits for the product, including marketing, R&D, operations, accounting, and finance costs. The company then uses the sales and costs figures to analyze the new product's financial attractiveness.
5) Product development: So far, for many new-product concepts, the product may have existed only as a word description, a drawing, or perhaps a crude mock-up. If the product concept passes the business test, it moves into product development. Here, R&D or engineering develops the product concept into a physical product. The product development step, however, now calls for a large jump in investment. It will show whether the product idea can be turned into a workable product.
The R&D department will develop and test one or more physical versions of the product concept. R&D hopes to design a prototype that will satisfy and excite customers and that can be produced quickly and at budgeted costs. Developing a successful prototype can take days, weeks, months, or even years. Often, products undergo rigorous functional tests to make sure that they perform safely and effectively.

Mohammad Arif, ME, MIET(UK), CEng

Wednesday, 16 January 2013

Hydraulic Hoses and Fittings Selection- Guideline

Hydraulic Hoses and Fittings Guideline
1.0 What is Hose????
Hose is a flexible tube used to carry fluid from one location to other.
2.0 Construction:
2.1.0 Inner tube: The inner tube carries the fluid. It should be flexible and needs to be compatible  with the type of fluid it will carry. The tube is usually made of synthetic rubber, Teflon or thermoplastics.
2.1.1 Reinforcement layer: The reinforcement layer consists of one or more sheaths of braided wire, spiral-wound wire, or textile yarn.
2.1.2 Protective outer layer: The outer layer is often oil, weather and abrasion-resistant. This depends on the type of environment the hose is designed for

3.0 Material:
Hoses are made from one or a combination of many different materials.
·         Nylon
·         Polyurethane
·         Synthetic rubber
·         PTFE
·         Stainless Steel



4.0 Hose Application:
Hoses are selected based on application, like pressure line, tank line, pilot line and suction line. Based on the application, hoses are categorized into 3 types
High pressure hoses: System with 220+ bar pressure hose type: SAE 100R12/R13/R15 , 4 to 6 wire breaded steel reinforced layers, bending radius will be more , harder  , available in different sizes. Where to Use: Pressure line
Medium pressure hoses: System with 150+ bar pressure Hose type: SAE 100R16/R17/R1/R2 , 2 to 4 layer of reinforcement of steel wires, Where to use : Pressure line
Low pressure hoses: System with 5-10 bar, Hose type: SAE 100R1 & 4 . The suction line should be full size; as straight as possible; have no or the minimum number of fittings; never include a standard pipe union and be completely sealed.  Where to use: Tank line, leakage line
Note: Pressure rating varies as hose sizes are goes up for even same type of hoses.

5.0 Hose Selection
Seven easy steps for selection of proper hose:

STAMPED:
Size: Dash size for proper flow and velocity (refer nomogram)

Temperature: working temperature limits should be considered

Application: where, when, what, statutory requirements etc

Material to be conveyed: Select based on hydraulic oil

Pressure: System working pressure & spike pressure

End connectors/couplings: identify end connectors needed

Delivery (Volume & velocity): Determine I.D. is sufficient for fluid transfer

6.0 Hydraulic Fitting selection
Fitting identification: Most fluid piping system sizes are measured by DASH NUMBERS.
What is DASH NUMBERS: These are universally used abbreviations for the size of components expressed as numerator of the fraction with the denominator always being 16.

For example: DASH- 04 ports is 4/16, means ¼ inch


There are many coupling systems, American, British, French, German and Japanese

American Standard
NPTF
NPSF
NPSM
SAE 514-ORB type
SAE 514 37 deg- JIC
SAE J512 45 deg
SAE J 1453- ORFS type
SAE J 512 Inverted flare
SAE J 1467 Clip fastener
SAE– J518- O-ring flange

British Standard
BSPP- British Standard Pipe Parallel
BSPT- British Standard Pipe Tapered

German Standard
DIN 2353 24 deg. cone
DIN 3863 60 deg. cone


6.1.0 DASH Numbers, NB, Thread

DASHHose dia( NB)Iron Pipe(NB)Thread
InchMetricMetricBSPPUN-UNF
-41/4''661/4''-199/16''-18
-55/16''88-10.3/8''-1911/16''-16
-63/8''108-10.3/8''-1911/16''-16
-81/2''13121/2''-1413/16''-16
-105/8''1614-165/8''-141.0''-14
-123/4''1918-203/4''-141 1/16''-12
-161''2522-251.0''-111 5/16''-12
-201. 1/4''3228-321. 1/4''-11 1 5/8''-12
-241. 1/2''3835-38-422.0''-111 7/8''-12
-322.0''51502.0''-112 1/2''-12

6.1.1 Various Fittings comparision




 

FEATURES COMPARISON OF TUBE FITTINGS
Feature
ORFS
JIC 37
BSP
Performance
Pressure capability
Very high
Medium to high
medium to high
Seal reliability
Excellent
Good
Very Good
Elastomeric steel
Metal to metal seal
Elastomeric steel
High tolerance to minor surface imperfections and damage.
Low tolerance to minor surface imperfections and damage.
Low tolerance to minor surface imperfections and damage.
Vibration resistance in rigid system
Excellent
Good
Very Good
Tube Compatibility
Wall thickness
All
Medium
Medium
Critical features
OD Tolerance and hardness for flat tube. OD tolerance only for brazed tube
ID finish, wall thickness uniformity(concentricity) and hardness
OD tolerance and hardness
Assembly
Tube preparation
Easy and quick
Easy and quick
Easy and quick( slower for welded pipe)
Inspection
Easy and quick
Easy and quick

Ease of installation
Excellent, minimum skill and training required because of high tolerance to assembly variations.
Good. Low tolerance to assembly variations. Requires skilled and trained personal
Good. Low tolerance to assembly variations. Requires skilled and trained personal
Ease of maintenance
Excellent, no tube entry
Very good, small tube entry
Good. Large tube entry
Temperature capability adopters w/o O-rings
Steel
Tube to be used only with O-ring
Good
Good
Stainless steel
Good
NA
Brass
Good
NA
Temperature capability adopters with O-rings
All style of Adopter
30 to 120 Deg C
30 to 120 Deg C
30 to 120 Deg C
 
ORFS fittings are most suitable and recommended for zero leakage and high pressure

7.0 Applicable Standard for hoses
SAE J343 -- Tests and procedures for hose & hose assemblies
SAE J514 --  Hydraulic tube fitting 37° flare, pipe fittings
SAE J515 – Hydraulic o-rings
SAE J518 – Code 61 & 62 four bolt split flange connections
SAE J1065 – Pressure ratings for hydraulic tubing
SAE J1453 – ORFS fittings with SAE port ends
SAE J1644 – Test methods for fluid connectors
SAE J846 – Coding system for identification of fluid connectors

8.0 Hydraulic Hoses Supplier
v  Manuli hydraulics
v  Alfagoma
v  Gates International
v  Aeroquip
v  Parker
v  Simprit
v  Imperial Auto
v  Hydroline
v  PSI Hydraulics

Mohammad Arif, ME, MIET(UK), CEng
Chartered Engineer. 

 






 

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