Re: the difference between the bright piston and the dark piston

Back your questions in details:

“Per TY290X piston, you have two types’ pistons; one is dark color and the other in bright color like stainless steel. So which is better and what’s the difference.

1. Three ways of piston surface treatment.

There are three ways:

a) Tin plating

b) Spray-plating with lead at piston skirt part.

c) Anodizing Aluminum process

Today, most of the piston adopts the lead spray-plating. It can strengthen the hardness and make the piston stronger than the pistons treated by the other two ways.

2. Spray-plating with lead at piston skirt part.

Before the spray plating, the piston can be treated by two ways:

a) Phosphating, piston plated in the acidic liquor with has phosphorus. So the piston is coated with the phosphorus film and then the piston is in black color.

b) Roughening, the piston is treated in the alkaline liquor then use the acidic liquor to make the piston shinning in silver color.

3. The performance of the two type’s pistons, silver color and dark color.

All the two types can well guarantee the quality according to its design. So kindly explain that to the end user that both have the same performance.

4. Why the piston manufacturers choose the spray-plating with lead in roughening way.

Because ANOTHER treatment is not economic and the roughening treatment before cementite can save 26 time the cost than ANOTHER treatment,

In order to know more information about piston, I want to discuss with you so as to give you some help when you introduce the piston to your customers.

Surface Treatment Type:

1) Piston with Pottery on the Surface

Pottery on the surface of the position is a hardness layer. Which is laid on surface of the piston and the thickness of it is 300um ,The hardness of the layer can reach 2000HV .It exists in the way of binding meta-lurgy .The principal composition of the layer is -A1²O³ and γ-A1²O³ .The use of his layer improve the wear-resisting and corrosion –resisting performance ,The well-distributed unseen tiny holes on the surface of the layer after oxidation contributes to the formation of the oil film when the piston is working .And the lubrication performance of the piston surface has also been improved .This item has been placed in to the national “863” projects .It was appraised by the exports from the science and technology ministry in 2002 .technical parameter comparison.

2) Piston with Graphite on the surface

The quality of the graphite is lubricative, high compressive strength ,heat-resistant,good heat transmit ,stable temperature,corrosion resistant,low friction(0.11 in ordinary)so when the piston is sprayed with graphite in skirt,the position is improved not only the initial work quality but also dropped the friction between the position and cylinder. That’s why there will be some engine choose the black type.

3) Piston with Tin on the Surface

Piston plated by 0.5-3u tin on the surface in chemical way ,the tin layer with little hole has the lubri-cative quality of soft metal .it can absorb more lubricative oil to drop the friction between the piston and cylinder.This type is the one we often mentioned as “no black one”.

4) Piston with Silk print on the Surface

The print can make logo and improve the piston life. If Lotus can in good need of the piston, he can use Lotus logo.

5) Piston with bottom antioxidation treatment

This can improve the piston anti-oxidation and enlarge the life.

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