Med en gang kvalitetskontrollen er ferdig, settes merkelappen på.

Here, med en gang means as soon as or immediately when.

So in this sentence, it introduces a time clause:

• Med en gang kvalitetskontrollen er ferdig = As soon as the quality control is finished

Even though the words literally look like with one time, you should learn med en gang as a fixed expression.

A few similar time expressions are:

• så snart = as soon as
• når = when
• idet = the moment / just as

In everyday Norwegian, med en gang is very common.

Because Norwegian usually forms compound nouns as one single word.

So:

• kvalitet = quality
• kontroll = control
• kvalitetskontroll = quality control

Then the sentence uses the definite singular form:

• kvalitetskontroll = quality control
• kvalitetskontrollen = the quality control

Notice the -s- in the middle: kvalitetskontroll. That linking -s- is very common in Norwegian compounds.

English often writes these as separate words, but Norwegian usually does not.

Er ferdig means is finished / is done.

Here, kvalitetskontrollen is a singular noun, so the sentence uses:

• er ferdig = is finished

If the subject were plural, you would often use:

• er ferdige = are finished

For example:

• Kontrollen er ferdig = The inspection is finished
• Kontrollene er ferdige = The inspections are finished

Could you say blir ferdig? Sometimes yes, but it changes the nuance:

• er ferdig = is finished / has reached a finished state
• blir ferdig = becomes finished / gets finished

In your sentence, er ferdig is the most natural choice.

This is because of the Norwegian V2 rule: in a main clause, the finite verb normally comes in the second position.

The sentence begins with a subordinate clause:

• Med en gang kvalitetskontrollen er ferdig

After that, the main clause starts. Since the time clause takes the first position, the finite verb must come next:

• settes merkelappen på

So the word order is:

1. Med en gang kvalitetskontrollen er ferdig
2. settes
3. merkelappen
4. på

If you started directly with the subject, it would be:

• Merkelappen settes på med en gang kvalitetskontrollen er ferdig.

Both are possible, but after a fronted time clause, Norwegian normally uses inversion:

• ..., settes merkelappen på.

This is very important for English speakers, because English does not usually do this.

Settes is the passive form of sette.

• å sette = to put / to place
• setter = puts
• settes = is put / is being put

So:

• Merkelappen settes på = The label is put on

The -s ending is a common way to form the passive in Norwegian, especially in formal, technical, or process-based language.

Compare:

• Vi setter merkelappen på. = We put the label on.
  active
• Merkelappen settes på. = The label is put on.
  passive

This kind of passive is very common in instructions, manufacturing, procedures, and formal descriptions.

Because the verb here is really sette på, which is a multi-word verb.

• å sette på = to put on / attach / switch on, depending on context

In this sentence, it means put on / attach.

In Norwegian, the particle (på) is often separated from the verb, especially in ordinary clause structure:

• Vi setter merkelappen på.
• Merkelappen settes på.

So på at the end is completely normal.

This is similar to English phrasal verbs:

• put on
• turn on

Compare:

• Han tar jakken på. = He puts the jacket on.
• Lyset slås på. = The light is switched on.

So på belongs with settes, even though it appears later.

Because they are both definite singular nouns of common gender.

In Norwegian:

• en kontroll = a control / an inspection

• kontrollen = the control / the inspection

• en merkelapp = a label
• merkelappen = the label

So the -en ending here means the.

This is one of the biggest differences from English: Norwegian usually adds definiteness to the end of the noun instead of using a separate word like the.

So:

• kvalitetskontrollen = the quality control
• merkelappen = the label

Ferdig is an adjective, and here it means finished, ready, or done depending on context.

In the sentence:

• kvalitetskontrollen er ferdig

it describes the state of kvalitetskontrollen.

So grammatically, it works like an adjective after er:

• Maten er ferdig. = The food is ready.
• Jobben er ferdig. = The job is finished.
• Kvalitetskontrollen er ferdig. = The quality control is finished.

English speakers sometimes expect a participle-like construction, but in Norwegian, ferdig is extremely common in this kind of sentence.

Yes. The given sentence is passive and process-focused. A more active version would name the person or people doing the action.

For example:

• Med en gang kvalitetskontrollen er ferdig, setter vi merkelappen på. = As soon as the quality control is finished, we put the label on.

Or:

• Med en gang kvalitetskontrollen er ferdig, setter operatøren merkelappen på. = As soon as the quality control is finished, the operator puts the label on.

The passive version is often preferred when the actor is unknown, unimportant, or obvious from context.

That is why settes sounds very natural in technical or procedural language.

Yes, it is normal here because the sentence begins with a subordinate clause:

• Med en gang kvalitetskontrollen er ferdig, settes merkelappen på.

The comma helps separate the introductory clause from the main clause.

Structure:

• subordinate clause: Med en gang kvalitetskontrollen er ferdig
• main clause: settes merkelappen på

In modern Norwegian, comma rules are not always identical to English punctuation rules in every detail, but in a sentence like this, the comma is standard and helpful.

It sounds natural, but somewhat formal or process-oriented because of the passive:

• settes merkelappen på

This kind of wording is very common in:

• instructions
• manufacturing
• product descriptions
• official or technical writing

In casual speech, people might more often use an active sentence, such as:

• Når kvalitetskontrollen er ferdig, setter vi på merkelappen.
• Med en gang kvalitetskontrollen er ferdig, setter vi merkelappen på.

So the original sentence is absolutely correct and natural, but it has a slightly more formal, procedural tone than everyday conversation.