March 2016 Archives

Even when you manufacture products that ultimately save resources and energy, it is not acceptable to waste resources or energy during the manufacturing processes. The surface treatment plant not only has the environmental conservation measures but also has resource and energy-saving measures for the corresponding processes. Here is the list of adopted measures.

1. Most of the water discharged from surface treatment processes was used for washing and cleaning. Therefore, adopting an effective water washing method can save water resources.
2. Reducing the water usage also reduces the discharge amount of water. This also decreases the burden of effluent treatment.
3. Discharged water from this process contains valuable substances. Recovering and recycling these substances can save resources.
4. Purification of discharged water is an overriding imperative in terms of the environmental conservation. Therefore, adopt an advanced process of removing impurities and recycle water. This process can eliminate water drainage in some cases.
5. If it is not possible to recycle the metals collected from discharged water containing valuable substances at your own plant, send them back to mine processing facility such as a refining plant for recycling.
6. Utilize waste heat generated during the processes or natural environments to recycle them as heat sources for heating, drying, cooling, and more.

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#231 Conserving Resources and Energy for Surface Treatment

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In this section, we will look into the surface treatment and conservation of resources and energy.

Surface-treated products save resources and energy

Before looking into the resource-saving and energy-saving measures in the surface treatment processes, it has been validated that the surface-treated products themselves ultimately save energy and resources.

Let's see the structure of Seto-ohashi Bridge, for example. Using stainless steel known to have excellent antirust properties results in huge building expenses even though the bridge will have superior anticorrosion characteristics. However, without doing so, they have built this bridge to be strong enough and without requiring any maintenance for a long-term (approx. 20 years) by adopting structurally strong HTTS (High Tensile Strength Steel) while applying surface treatments including metallic spraying, hot dipping, and high-grade anticorrosion coatings.

As an example more familiar to us, adopting thinner steel plates has contributed to reducing the weight of automobiles while the industry is trying to make the automobiles more lightweight to improve the fuel efficiency and energy-saving performance. Surface treatments, such as applying zinc plating, zinc alloy plating, or coatings, are used to enhance the anticorrosion properties as well.

In Japan, approximately 100 million tons of steel are produced annually. They are used as industrial materials in varying characteristics to produce a variety of steel products. However, these steel materials will hardly be used as bare iron.Structurally strong steel is extremely prone to rusting. Therefore, surface treatments including hot dipping, electroplating, paint or coating application, and spraying are generally adopted in order to improve anticorrosion properties enough to maintain the functionality of steel products.

Case example requiring weight reduction: Railroad vehicles

As we have seen, we can conclude that the surface treatment process is a powerful technique to promote energy and resource conservation in manufacturing various products.

#230 Measures for Organic Solvents

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Because organic solvents are used in surface treatments including metal cleaning and painting, the employers are required to protect their employees under the provisions of the Ordinance on Prevention of Organic Solvent Poisoning. In addition, a leakage of organic solvents outside of the plant could cause troubles with the neighborhood due to its odor and health risks.

To prevent such incidents, the following steps have been adopted:

1. Use an appropriate hood to enclose the area where organic solvents are handled. Then, vacuum up by ventilation equipment.(local ventilation)
2. Use an activated carbon filter to absorb and remove organic solvents.
3. Discharge the absorbed air to the outside.

[Table 1] shows the capture velocity of local ventilation equipment. [Table 2] shows the required ventilation volume. In addition, [Fig. 1] illustrates the absorption and desorption processes of activated carbon absorption equipment.

[Table 1] Capture velocity of local ventilation equipment
Model/Type Capture velocity (m/s)
Enclosure 0.4
External Side suction 0.5
Bottom suction 0.5
Top suction 1.0

[Table 2] Required ventilation volume for ventilation equipment
Organic solvent categories Ventilation volume (m3/min)
Type 1 organic solvent (e.g. trichloroethylene) 0.3w
Type 2 organic solvent (e.g. perchloroethylene) 0.04w
Type 3 organic solvent (e.g. petroleum solvent) 0.01w

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(1) Scope

This section defines standards on electroless nickel and phosphorous alloy plating applied on the significant surfaces of metal (steel, copper, and aluminum) basis and their alloy substrates in order to add anticorrosion and abrasion-resistant properties.

(2) Grades, symbols, and minimum plating thickness, etc.

[Table 1] shows the details.

[Table 1] Grades, symbols, and plating thickness for electroless nickel plating and phosphorous plating
GradeMinimum plating thickness (µm)SymbolReference/Application
13 ELp-Fe/Ni-P3 or [1]
ELp-Cu/Ni-P3 or [1]

ELp-AL/Ni-P3 or [1]
Soldering
25ELp-Fe/Ni-P5 or [2]
ELp-Cu/Ni-P5 or [2]
ELp-AL/Ni-P5 or [2]
Anticorrosion and soldering
310ELp-Fe/Ni-P10 or [3]
ELp-Cu/Ni-P10 or [3]
ELp-AL/Ni-P10 or [3]
Anticorrosion and abrasion resistance
415ELp-Fe/Ni-P15 or [4]
ELp-Cu/Ni-P15 or [4]
ELp-AL/Ni-P15 or [4]
Anticorrosion and abrasion resistance
520ELp-Fe/Ni-P20 or [5]
ELp-Cu/Ni-P20 or [5]
ELp-AL/Ni-P20 or [5]
Anticorrosion and abrasion resistance
630ELp-Fe/Ni-P30 or [6]
ELp-Cu/Ni-P30 or [6]
ELp-AL/Ni-P30 or [6]
Anticorrosion and abrasion resistance
750ELp-Fe/Ni-P50 or [7]
ELp-Cu/Ni-P50 or [7]
ELp-AL/Ni-P50 or [7]
Anticorrosion and abrasion resistance

(3) Chemical composition of plating film

[Table 2] shows the details.

[Table 2] Chemical composition of plating film
Element nameNiPOther elements
% 83 to 98 2 to 15 0 to 2

(4) Hardness of plating film

Use a micro Vickers hardness meter to measure the hardness. Set the hardness at Hv500 or greater. Depending on the heat treatment, set a value from Hv600 to 1000. (The plating thickness of this measurement sample must be at least 50 µm.)

(5) Plating adhesion

Perform a bending test to make sure that the plating is free from flaking or swelling. The adhesion improves by the heat treatment processes described in [Table 3].

[Table 3] Heat treatment for adhesion improvement
Basis metalTemp. (°C)Time (h)
Steel and steel alloy210±101 to 1.5
Copper and copper alloy190±10
Aluminum and aluminum alloy (non-heat-treatable)160±10
Aluminum and aluminum alloy (heat-treatable)130±10

(6) Corrosion resistance of plating

This property can be measured by a neutral salt spray test, etc

(7) Abrasion resistance of plating

This property can be measured by a reciprocating wear test.

(8) Solder wettability of plating

Perform a test similar to that used for industrial silver plating.

(9) Hydrogen embrittlement removal after plating

If it is necessary to perform another heat treatment on a thermal-treated steel product for hydrogen embrittlement removal, perform the treatment at 190 to 230°C within four hours from the plating work. The heating time varies depending on the plating thickness and should be determined and agreed between the parties concerned.

(10) Symbol

ELp-Fe/Ni(90)-P 20

Electroless nickel plating consisting of 90% nickel and 10% phosphorous, 20 µm thick on a steel substrate

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