Lessons · Lesson 5 of 7
- 01 · The machine is the size: needles, cylinders and a bank you cannot borrow from
- 02 · The dozen pair, and the five denominators on one cost sheet
- 03 · The toe: one seam, three ways to close it, and the money between them
- 04 · Boarding: the operation that makes the measurement
- 05 · A size that is a range
- 06 · Recovery: the number that is not on the measurement sheet
- 07 · Pairing, packing and the multiplier
A size that is a range
What it means that one sock fits four shoe sizes, and where the cost of a small size range actually lands.
Lesson 5 of 7 · 17 min
One sock, four feet
HS-244 comes in 35-38, 39-42, 43-46 and 47-50. Each of those covers four European shoe sizes. One physical sock has to fit a foot at the bottom of its range and a foot at the top of it. What makes that possible is not tailoring. It is that the fabric stretches and comes back.
Course 18.5 covers what a shoe size is, and why the British, American and Continental scales disagree. That is the returns side of it, and it is not repeated here. On the making side, what matters is the consequence:
Where the size chart really comes from
Lesson 1 fixed the two ends of it. Bank A's 144-needle cylinders are the smallest in the house, so nothing below a 35-38 exists, and bank C's six machines are the whole of the large capacity. Lesson 4 fixed the steps between: each range needs 48 boarding forms of its own, at USD 34 each.
So the four ranges on Quillan's chart are not four points on a grade rule. They are four cylinders, four sets of forms, four sets of point-of-measure figures, and one more thing nobody counts. Each range multiplies the number of stock-keeping units, or SKUs. An SKU is one sellable line: one style, one colour, one size, one barcode.
Four size ranges times four colours is 16 SKUs from one style. Each has its own barcode, its own carton label, its own pick face in the warehouse, and its own dye lot. That last one is where the money is.
The size that costs the most is the smallest one
Tanyeri dyes finished socks in a rotary machine that holds 200 kg of goods. The cost of running it has two parts. Dyestuff and chemicals cost about USD 0.42 a kg of goods, and that rises with what is in the machine. Machine time, labour, water and steam cost about USD 136 a load, and that does not move at all. At a full load the two together come to USD 1.10 a kg, which is the figure lesson 2 used.
A colour and a size cannot share a bath. So the size of the load is set by the smallest quantity on the order.
| Size range | Dozen pairs a colour | Grams a pair | Kilogrammes in the bath | Load cost, USD | USD a kg |
|---|---|---|---|---|---|
| 35-38 | 90 | 62 | 67.0 | 164.12 | 2.45 |
| 39-42 | 756 | 74 | 671.3 | full loads | 1.10 |
| 43-46 | 792 | 84 | 798.3 | full loads | 1.10 |
| 47-50 | 162 | 94 | 182.7 | 212.75 | 1.16 |
Read the last column. The 35-38 is dyed at USD 2.45 a kilogramme, against the USD 1.10 that was quoted. The reason is that 67 kilogrammes are being turned round a machine built for 200. Across four colours that is USD 362 the cost sheet does not carry, which is USD 1.01 a dozen pairs on that size, or 8.8% of the price of the goods.
And the size everybody worried about, the 47-50, is nearly fine. 182.7 kilogrammes is most of a load, and the penalty is USD 47 across four colours.
What to do about it
The 35-38 is 360 dozen pairs. At the quoted margin of USD 1.19 a dozen pairs it brings in USD 428 on the order, and the dye penalty takes USD 362 of that back. Its real contribution is USD 66.
That is not an argument for dropping it. Whether a range needs its smallest size is a range decision, and course 16.2 is where that argument belongs. An option can be worth carrying at no profit, and a customer who cannot find their size buys the whole five-pack somewhere else. It is an argument for buying it differently.
Order the 35-38 for two seasons in one dye lot. Putting 134 kilogrammes in the bath instead of 67 brings the cost to USD 1.44 a kilogramme, and the penalty on four colours falls from USD 362 a season to USD 90. That is USD 272 a season recovered. What it costs you is holding half a season of the slowest size: about 180 dozen pairs of stock, at a made cost of roughly USD 1,838.
Whether that trade is worth taking depends on how sure you are that the colour will still be in the range next season. That is a merchandising question with a real answer. But nobody asks it, because the dye penalty never appears as a line on anything.
The label, and the market boundary
Quillan sells HS-244 in the United Kingdom and in Denmark. The Continental range on the label is 39-42. The British equivalent is roughly UK 6 to 8. The two scales do not step at the same places. So a foot at the boundary sits in one range on one label and in the next range on the other, for the same sock.
There are two routes:
- Two labels, two SKUs. The 16 SKUs become 32. Each needs artwork, a barcode and a pick face, at about USD 85 of artwork and set-up each: USD 1,360, plus a permanent doubling of the range's SKU count.
- One dual-marked label carrying both scales on one header card. One set of artwork, one SKU list, and a customer who has to read two numbers.
Route 2 is cheaper, and it is what Quillan does. The reason is worth saying out loud, because it is the general rule: in hosiery the number on the label is a conversion, not a measurement. So putting two conversions on one card costs nothing but print. It is a decision you can make freely, unlike almost everything else in this course.
Check yourselfYour buyer wants to split the 39-42 into a 39-40 and a 41-42 to improve fit. What do you need to tell them before they take it to the range meeting?Show the answer
Tell them it is a machine and tooling question, not a fit question, and that three numbers answer it. First: will 168 needles and a stitch-length change really make two sizes a customer can tell apart? Probably not, because a four-size range is roughly what one cylinder covers, so one of the two will need a different cylinder. Second: each new range needs 48 boarding forms at USD 34, so USD 1,632 and three weeks. Third: splitting one range into two halves the dye-lot size of each, so sizes that were filling a 200 kg bath may stop filling it. The buyer is entitled to make the change. They are not entitled to be surprised by it in July.
Prompt · Schedule a sock order by cylinder, not by total
Before you accept a delivery date on a hosiery order, or the first time a mill answers a capacity question with one number.
Act as a hosiery production planner in a sock mill. I need a knitting schedule built per machine bank rather than as one pooled figure, because a sock size cannot move to a machine that was not built for it. Order facts: buyer [BUYER], PO [NUMBER], style [STYLE], total [QTY] dozen pairs, price [AMOUNT] a dozen pairs, terms [TERMS], required at [DESTINATION] on [DATE]. Size ranges and their share of the order: [LIST EACH SIZE RANGE AND ITS PERCENTAGE]. The mill's machine list: [FOR EACH BANK, GIVE CYLINDER DIAMETER, NEEDLE COUNT, NUMBER OF MACHINES, WHICH SIZE RANGES IT CAN HOLD, AND THE CYCLE TIME IN MINUTES A SOCK FOR EACH OF THOSE SIZES]. Running minutes a machine-day: [NUMBER]. Do the following. First, convert every size range into pairs and then into machine-days on the bank that can actually knit it, and show the arithmetic. Second, give me calendar days PER BANK and tell me which bank finishes last, because that is the order's knitting date. Third, calculate the pooled figure a planner would get by dividing total pairs by total daily capacity, and state the gap between the two in days. Fourth, name any size range that is over-represented relative to the capacity that can make it, expressed as its share of the order against its share of the daily capacity. Fifth, tell me what the late bank does to the shipment: whether it misses the booked transport, what a part-load or a split delivery would cost, and what that is as a share of the order's margin if I give you the margin. Sixth, list the size ranges the mill cannot make at all with this machine list, and say what equipment would be needed. Do not give me a single number for the order, and do not average cycle times across banks. If a cycle time is missing, ask for it rather than assuming one.
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