As a part of the journey, we have been additionally invited to Sigma’s one and solely manufacturing unit within the mountainous area of Aizu, the place we have been handled to an excellent tour of the manufacturing unit to see how the corporate manufactures all its lenses and cameras in-house from begin to end.
Earlier than we might start, it was necessary to placed on shoe coverings and lab fits to keep away from any contamination. One of many foremost mottos of the meeting division is to not deliver mud into the surroundings, so some staff must cross by way of air showers earlier than getting into clear rooms throughout the manufacturing unit.
First up was the Manufacturing Engineering & Improvement Divisions, the place Sigma’s manufacturing and growth engineers can work and talk freely and simply.
Subsequent up a fast stroll previous the Prototype Jigs & Instruments Processing Division, the place components for prototypes are machined for the engineers to work by way of any teething issues, and determine any defects earlier than the molds and dies are finalized for mass manufacturing within the Mould & Die Manufacturing Division.
Every mould can take between six to eight weeks to complete and the division creates roughly 13 resin molds and eight press dies on common per 30 days. Sigma’s smallest mould weighs a hefty 100kg, whereas many weigh over a ton!
(Picture credit score: Dan Mould)
Onto the Steel Processing Division, the place round 15,000 components are processed per day by 200 machining instruments utilizing aluminum, brass and chrome steel. The components produced on this division are for digicam our bodies, lens barrels and even small electrical contact pins, and have tremendous strict tolerances from +/-0.003 to 0.005mm (which is 10 occasions thinner than a human hair!).
Additionally within the Steel Processing Division, Sigma was keen to point out off its newest addition – a number of five-axis CNC machines put in particularly for the brand new Sigma BF digicam, which is machined out of a single block of aluminum.
That is loaded and unloaded by automated robots after which taken to the subsequent machine for additional processing. The whole course of takes seven hours for every digicam!
Plastic Unbelievable
(Picture credit score: Dan Mould)
Subsequent up, the Plasticity Division! Plasticity doesn’t simply relate to plastic, although; this division encompasses all the pieces from injection molding to metallic urgent and stamping, portray, electroplating and even printing.
We caught a glimpse of Sigma’s spectacular machines that create the plastic injection molding, with the corporate storing 1,500 molds prepared to make use of within the course of to create plastic parts, and we noticed them reside in motion creating the model’s iconic lens caps.
At least 38 machines are used to provide the plastic parts utilizing supplies akin to engineering plastic (EP) and thermally steady composite (TSC).
Resin granules are dried in a hopper at excessive temperatures, then melted down at round 572°F / 300°C and injected into the mould, the place they re-solidify into the designed form. Extra plastic is eliminated and floor as much as be recycled.
Onto Steel Urgent & Stamping, and right here dies are utilized by high-powered equipment to stamp or press out metallic components akin to diaphragm blades, washers, clips, pins, metallic guides and extra. The supplies used within the division embrace chrome steel, iron, aluminum, copper and brass.
There are two forms of die: Progressive Die, which makes use of a number of urgent processes in sequence to create the ultimate half from the metallic materials. Not solely cuts, but in addition bends, and “punches”. Then there’s the Single-Shot Die, which creates the half in a single shot.
A lick of paint
(Picture credit score: Sigma Imaging)
The Portray Division is chargeable for bettering the floor properties of supplies, primarily to boost hardness, put on resistance, lubrication, corrosion resistance, oxidation resistance, warmth resistance, insulation, and ornamental and aesthetic qualities.
The division makes use of 5 several types of machines to hold out varied forms of portray, together with a complicated twelve-axis machine that may intently mimic human-like actions.
We additionally took a pit cease on the Printing Division, the place we noticed machines printing the lens data discovered on the outside of the lens, akin to emblem, focal size and f-values. That is primarily accomplished by Pad or Silk Display screen printing. Some Sigma lenses and cameras additionally require colour inlay, which is a fragile course of and must be accomplished by hand.
A Sigma consultant instructed us, “Since nearly all printing right here is seen from the outside of the lens, the eye to element is of utmost significance to create high-quality merchandise”.
Subsequent it was onto the Electroplating Division, the place we noticed parts being electroplated and anodized. Within the electroplating course of, brass, iron, metal, phosphor bronze and zinc supplies are handled with nickel and nickel-chrome plating to enhance abrasion resistance, corrosion resistance, and lubricity bettering sturdiness and look. The anodizing course of is comparable, however creates an alumite coating on aluminum supplies.
We witnessed first-hand Sigma lens bayonets being electroplated, with Sigma’s chief of customer support, Jonathan Ryan, telling us, “We imagine {that a} fantastically coated and unadulterated bayonet helps to make a powerful first impression when customers first open up the lens field and take out their new lens”.
Glass Molding
(Picture credit score: Dan Mould)
Now onto the Glass Molding Division – the world that creates the magical glass that goes inside a Sigma lens.
This division molds particular aspherical lenses from glass gob (a measured quantity of molten glass minimize from a stream of glass and fed right into a molding machine) or blows it right into a pre-form, with the melted glass taking over the specified form and setting as soon as cooled.
Sigma produces spherical lenses as effectively, with grinding and sprucing processes which we’ll see later, however these aspherical lenses can suppress aberrations and enhance optical efficiency and they’re an important key consider growing design freedom.
One in all Sigma’s main strengths is its means to provide large-diameter aspherical lenses with diameters in extra of 80mm, that are utilized in ultra-wide-angle lenses . Sigma instructed us that 70 machines are used to provide 10,000 items per day.
The molding machines carry out three processes: preheating, urgent, and cooling, reaching temperatures of as much as 1,292°F / 700°C with pressures of 500-1000kg being utilized to mould the lenses. It takes a minimal of 20 minutes to mould a single lens, with the longest taking about 2.5 hours.
Onto the Extremely-Precision Machining (GM Molds) division now, and that is the place the molds for the GM division are manufactured. The Glass Molds use three foremost processes: tough machining, ending machining and hand sprucing.
Every mould is fabricated from tungsten carbide and is far heavier than it appears; a 4cm dice weighs round 1kg! These molds are used to make aspherical lenses, so their precision is very necessary for creating ultra-refined aspherical lens components.
Processing and becoming the lenses
(Picture credit score: Sigma Imaging)
As you may think, the division identified for processing the lenses and mounting them contained in the barrel is huge for the world’s largest impartial lens producer. The Optical Components Processing division is separated into Lens Coating, Lens Centering, Optical Component QC and Washing, Superb Sprucing, Edge Portray, Lens Bonding and Lens Caulking.
First up, the lens is centered (to search out its optical middle) after which the outer diameter is floor away to achieve the ultimate lens design. There are between 10-28 lens components inside a Sigma lens, so it’s essential for all of them to achieve a constant middle for high-resolution picture high quality.
Sprucing is vital to reaching a pointy and vibrant lens, so it’s divided into three phases: Curve Era, Tough Sprucing and Superb Sprucing.
As seen earlier, Sigma molds its aspherical optical components from glass gobs. On this division, the spherical optical components are floor and polished from pre-formed glass “blanks”. Sigma is ready to obtain extremely excessive precision on this course of, the place solely 0.05 – 0.1mm of fabric may be polished away at a time.
Lenses should be washed after ultimate processing and generally even between processes. The washing course of is a 12-step course of that makes use of recent water from the Bandai space in Japan, in addition to isopropyl alcohol, and ultrasonic pulses to wash away the sprucing residue. Some optical components embrace glass so smooth that it could possibly be scratched by the washing course of, so they’re additionally washed by hand.
Now onto lens coatings, and right here we noticed the employees making certain that every aspect is freed from mud, residue and blemishes earlier than loading them into “domes” to be carried off to the coating machines.
Sigma makes use of its proprietary “Tremendous Multi-layer Coating”, which is an anti-reflectance coating utilized utilizing a vacuum deposition course of. Since, naturally, 4-5% of sunshine is mirrored per facet of the lens aspect, and there are 10-28 optical components per lens, you may see how the lack of mild will add up.
The Tremendous Multi-layer coating achieves larger mild transmittance per lens aspect, which permits Sigma to make merchandise with sooner apertures. The variety of layers of coating vary from 1-15, with every layer being solely 300-500 nanometers (0.0003-0.0005mm) thick.
Typically a gaggle of lens components must be bonded collectively to appropriate picture defects (“aberrations”) that naturally happen in spherically-shaped lenses. The weather are joined utilizing a UV-cured resin, with a few of them utilizing a balsam-based resin.
One facet of lens manufacturing I hadn’t thought of was minimizing reflectance contained in the lens barrel. Sigma does this by retaining the within as darkish as attainable, and hand-painting the rim of its glass edges with black ink or paint in a course of referred to as ‘Sumi-nuri’.
Ryan revealed that the corporate is engaged on automated machines to be used on this part, although it’s at present such a fragile course of that it must be accomplished by hand. I additionally had the prospect to quiz his brains on Vantablack – the world’s blackest materials, which makes use of carbon nanotubes to soak up virtually all mild, and he instructed me it was one thing the corporate is inquisitive about.
With the lens components centered, polished, washed and the perimeters hand-painted, it’s time for meeting within the Lens Caulking space. Right here, the optics are press-fitted into lens chambers utilizing excessive warmth and strain to safe them in place, whil different lenses are screwed into the chamber.
Lastly, one in every of Sigma’s own-made circuit boards is added to the lens.
The ending touches
(Picture credit score: Sigma Imaging)
The tour concluded with a stroll by way of Sigma’s Meeting Division. All of the components we’d seen so far are gathered and assembled into the ultimate merchandise. This space is a strict clear room surroundings, to maintain as a lot mud out of our lenses as attainable.
We acquired to see the Sigma 24-70mm f/2.8 DG DN II Artwork lens, which is the corporate’s newest huge vendor, being assembled in entrance of our eyes with the person components assembled into models, that are then adjusted and the decision examined.
From the window we might see two automated machines: one making use of the correct amount of grease alongside the cam barrel grooves, and the opposite inserting rollers. Each require precision for the very best final result.
All assembled lenses are adjusted and inspected by Sigma’s A-1 MTF (Modular Switch Perform) measurement machines, which have been developed in-house and are outfitted with ultra-high-resolution sensors.
Subsequent up it’s the High quality Assurance division, which makes use of Sigma’s MTF measurement machines from Trioptics to totally consider the efficiency of latest lens designs in addition to the efficiency of opponents’ lenses.
The lenses may be evaluated from minimal focus distance all the best way to infinity, to get super-accurate efficiency knowledge throughout the total focus spectrum.
One of many machines has been in use for round 5 years and is kind of uncommon, with there solely being just a few of them in Japan, whereas one other machine was custom-ordered from Trioptics and is the one one in every of its sort on the earth.
These machines are used to examine every lens to make sure it meets Sigma’s strict decision requirements, and supply the benchmark scores utilized by the A-1.
Lastly, the High quality Assurance division is chargeable for the general high quality management of Sigma merchandise. Since model picture is strongly related to high quality, this division carries out uncompromising and rigorous high quality checks; not solely on assembled merchandise, but in addition on particular person models in addition to pre-production firmware bug checking and digicam compatibility checking.
Taking a guided tour by way of each step of Sigma’s manufacturing course of was fascinating, instructional and an actual privilege – and gave us a brand new appreciation for the true craftsmanship that goes into creating these unbelievable cameras and lenses. Thanks to Sigma for the good honor of visiting the Aizu facility!
