Our Management System Certificates

What the certificates cover

All eight certificates were issued for the same manufacturing scope: manufacturing of metal chains (except for articulated connection chain) and parts, springs and spring leaves, coated or core wires, rods, tubes, plates and electrodes — except those used in electrical works and those with electrical insulation.

That scope covers everything we do at the Biga plant: agricultural implement and machinery springs, industrial compression and extension springs, torsion and form parts, and wire form production.

The certificates were issued by Ekol Belgelendirme Şirketi (Maslak, İstanbul). Each certificate number is listed below and can be checked on the certification body's own lookup page. All eight are also available as a single PDF.

A certificate is a commitment to method, not a guarantee of performance

A management system certificate does not guarantee that a product will reach a particular performance figure — that needs saying plainly. What it says is that a written order for how the work is done has been established and has passed an independent audit.

In spring manufacturing that has a practical meaning: which wire came from which batch, which heat treatment regime was applied, who checked the dimensions and with what instrument — all of it recorded. If a part fatigues earlier than expected in the field, it can be traced backwards.

For the technical properties of the product itself, look at the dimensions rather than the certificate: wire diameter, coil count, leg angle and material. Those are stated separately on every quotation, and final production is verified against the real values on the wire supplier's certificate.

Wire tensile strength — what the mill certificates say

Spring steel strength is often called "hardness" in the field, but spring wire is bought on tensile strength (N/mm²), not on a Rockwell figure. That is what a mill test certificate gives: every coil goes through a tensile test, a torsion test and a reduction-of-area measurement. The table below is the complete set of values written on the certificates for the wire we coil — nothing calculated, all read off the documents.

Tensile strength falls as diameter rises: 1.80 mm wire measured 1,870–1,890 N/mm² while 12.00 mm wire came out at 1,180–1,290 N/mm². That is not a quality difference but a rule of EN 10270-1 itself; thinner wire sees more deformation while being drawn and reaches a higher strength. The figure to use in a spring calculation is the one on that diameter's own row.

The difference between the two columns matters: "standard range" is the band in which the wire is acceptable for that diameter, "measured" is what the batch delivered to us actually produced. On all sixteen certificates the measured values sit inside the band. The origin of the wire rod is stated on the certificate too — for these batches Türkiye, Spain and South Korea.

Whose documents these are — the chain written out

The management system certificates were issued to Met-İş Çelik Yay: the company name, the Biga address and the manufacturing scope are printed on them. The mill certificates belong to a different chain: the wire is made by Çelik Halat ve Tel Sanayii A.Ş. and we buy it through Efeoğlu Çelik Halat, which is why Efeoğlu is the customer named on the certificate. We are not presenting those as our own certification — we show them so that the wire behind the spring is traceable.

The US company documents are here on the same logic: they are what stands behind the "In Partnership with USA Investment LLC" line in our footer. The company was organised in the Commonwealth of Virginia on 20 March 2026, and the IRS employer identification notice carries the same date. The number itself is masked in the image — an unmasked IRS notice is the most common input for business identity theft in the United States. If an official counterparty needs it, we provide it in writing.